WO2009128180A1 - Electromagnetic wave inhibitor and process for producing the electromagnetic wave inhibitor - Google Patents
Electromagnetic wave inhibitor and process for producing the electromagnetic wave inhibitor Download PDFInfo
- Publication number
- WO2009128180A1 WO2009128180A1 PCT/JP2008/071860 JP2008071860W WO2009128180A1 WO 2009128180 A1 WO2009128180 A1 WO 2009128180A1 JP 2008071860 W JP2008071860 W JP 2008071860W WO 2009128180 A1 WO2009128180 A1 WO 2009128180A1
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- WO
- WIPO (PCT)
- Prior art keywords
- electromagnetic wave
- moisture
- proof film
- wave suppression
- point
- Prior art date
Links
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Images
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Definitions
- the present invention relates to an electromagnetic wave suppressing body that suppresses unnecessary radiation of electromagnetic waves generated from electronic devices and the like, and a method for manufacturing the same.
- the conversion mechanism of electromagnetic waves into thermal energy is mainly classified into conductive loss, dielectric loss, and magnetic loss, and the amount of conversion of electromagnetic waves into thermal energy (radio wave absorption amount) is assumed by these three types of losses.
- the electromagnetic wave absorption energy P [W / m 3 ] per unit volume is expressed as Equation (1) using the electric field E, the magnetic field H, and the frequency f.
- the first term represents the conduction loss
- the second term represents the dielectric loss
- the third term represents the magnetic loss.
- magnetic sheets are mainly used for electronic devices, and in particular, affixed on printed circuit boards, flexible printed circuits (FPCs), upper surfaces of packages, and the like. It's being used.
- Various types of magnetic sheets have been developed, including a material in which a ferrite material or a metal magnetic powder is mixed with a resin and a carbon-based material. There are mainly two ways to use this magnetic sheet.
- electronic devices are also used in low-temperature environments such as cold districts and freezer rooms.
- a gel composition is used for an electronic device as an electromagnetic wave suppressor
- the moisture of the gel is frozen below freezing point, the dielectric constant of the gel composition is lowered, and the electromagnetic wave suppression function may not be exhibited.
- the electromagnetic wave suppression body converts electromagnetic waves into heat energy inside, high flame retardancy has been desired.
- This invention is proposed in view of such a conventional situation, and provides the electromagnetic wave suppression body which has high antifreezing property and high flame retardance, and its manufacturing method.
- the inventors of the present invention have determined the alcohol concentration of the acrylate polymer gel and the thickness of the electromagnetic wave suppression sheet in the electromagnetic wave suppression sheet having the acrylate polymer gel. It has been found that high antifreeze and high flame retardancy can be obtained by prescribing. That is, the electromagnetic wave suppressing body according to the present invention includes a first moisture-proof film, a second moisture-proof film, and an acrylate polymer sealed between the first moisture-proof film and the second moisture-proof film.
- the acrylate polymer gel contains x% by mass of alcohol, and the thickness ymm of the electromagnetic wave suppression sheet is point a in the xy coordinates (x, y).
- the manufacturing method of the electromagnetic wave suppression body which concerns on this invention contains alcohol of x mass%, an acrylate-type monomer, and a polymerization initiator between the 1st moisture-proof film and the 2nd moisture-proof film.
- the composition is injected and sealed, and the thickness ymm of the electromagnetic wave suppression sheet composed of the first moisture-proof film, the second moisture-proof film, and the acrylate polymer gel in which the composition is gelled is expressed as xy.
- FIG. 1 is a cross-sectional view of the electromagnetic wave suppression sheet in the present embodiment.
- FIG. 2 is a solubility curve diagram of sodium nitrate, potassium nitrate, potassium chloride, and sodium chloride.
- FIG. 3 is a graph showing the relationship between ethylene glycol concentration (wt%) and freezing point (° C.) at sodium chloride concentrations of 1.0 mol / L, 2.0 mol / L, 3.0 mol / L, and 4.0 mol / L. It is.
- FIG. 1 is a cross-sectional view of an electromagnetic wave suppressing body in the present embodiment.
- This electromagnetic wave suppression body has the electromagnetic wave suppression sheet 1 comprised by sealing the electromagnetic wave suppression material 12 between the moisture-proof films 11a and 11b. That is, the electromagnetic wave suppression sheet 1 has a thickness t2 in which the thickness t1 of the moisture-proof films 11a and 11b and the thickness of the electromagnetic wave suppression material 12 are added.
- the moistureproof films 11a and 11b have a thickness t1 of about 0.05 to 0.2 mm.
- the moisture-proof films 11a and 11b have excellent moisture-proof properties and prevent the moisture of the electromagnetic wave suppressing material from evaporating.
- the moisture-proof films 11a and 11b are formed by laminating a plurality of PET (polyethylene terephthalate) films with a barrier layer for preventing moisture permeation, such as metal oxide, with a thermoplastic resin, and sealing the sealing surface on the outermost surface. A thermoplastic resin for stopping is formed.
- a thermoplastic resin for stopping is formed.
- Kerrha Co., Ltd. Serer trademark
- the electromagnetic wave suppression material 12 is made of an acrylate polymer gel containing alcohols and an electrolyte. Since this gel compound contains alcohols and an electrolyte, the freezing point of the gel is lowered and the electromagnetic wave suppression function is stably maintained even in a low temperature environment. Alcohols that act as antifreeze are used.
- primary alcohols for example, primary alcohols, secondary alcohols, tertiary alcohols and higher are listed. Specific examples include methanol, ethanol, propanol, butanol, ethylene glycol (EG), propylene glycol (PG), pentaerythritol and the like. Among these, glycols are used from the viewpoint of functional expression and interaction with other compounds. Most preferred are ethylene glycol. An electrolyte that causes a freezing point depression of the solution is used. For example, those having high solubility in a polar solvent having a high dielectric constant can be mentioned.
- FIG. 2 is a graph showing the solubility of sodium nitrate, potassium nitrate, potassium chloride, and sodium chloride in water. This graph shows the mass of a solute dissolved in 100 g of solvent as a numerical value expressed in grams.
- potassium chloride and sodium chloride have a low solubility curve gradient and are less likely to precipitate crystals even with a slight temperature change, so that ions are stably maintained.
- Such an electrolyte is preferably a strong electrolyte that dissociates completely into ions in a solution, and examples thereof include sodium chloride, potassium chloride, calcium chloride, potassium acetate, and calcium acetate.
- the acrylate polymer gel has a three-dimensional network structure obtained by adding a polymerization initiator and a crosslinking agent to an acrylate monomer.
- This three-dimensional network structure is formed by a polymerization initiator that initiates a chain reaction between acrylate monomers, and a crosslinking agent that acts as a crosslink that links some of the side chains of the acrylate polymer. It is.
- the acrylate polymer gel contains x mass% alcohol, and the thickness (t2) ymm of the electromagnetic wave suppression sheet 1 is point a in the xy coordinates (x, y). It is desirable to be within a region formed by connecting three points of (10, 1.0), b point (10, 3.0), and c point (20, 1.0). Thereby, the electromagnetic wave suppression sheet 1 has high antifreeze and high flame retardance.
- the electromagnetic wave suppression body in the present exemplary embodiment has the adhesive layer 2 on at least one surface of the electromagnetic wave suppression sheet 1. That is, the adhesive layer 2 is disposed on at least one of the moisture-proof films 11a and 11b.
- the adhesive layer 2 includes a nonwoven fabric 21 that is a base material and an adhesive 22.
- PET polyethylene terephthalate
- PET polyethylene terephthalate
- PET polyethylene terephthalate
- the adhesive layer 2 has a thickness of about 100 ⁇ m to 200 ⁇ m.
- the nonwoven fabric 21 can have a function according to the purpose and application by combining a plurality of raw materials or adjusting the shape such as fiber length and thickness.
- these raw materials include aramid fibers, glass fibers, cellulose fibers, nylon fibers, vinylon fibers, polyester fibers, and polyolefin fibers.
- the adhesive 22 is a pressure-sensitive adhesive that can be applied to or immersed in a tape-shaped substrate made of the nonwoven fabric 21.
- the adhesive 22 has fluidity with respect to the adherend when pressure is applied, and also has cohesiveness with respect to peeling. Examples of such an adhesive 22 include acrylic resin-based resins.
- a double-sided tape can be obtained by synthesizing an acrylate monomer with a highly polar monomer to synthesize an adhesive and applying it to tissue paper (nonwoven fabric).
- the adhesive 22 preferably contains hexabromobenzene, antimony trioxide or the like as a flame retardant.
- an electromagnetic wave suppression body will have a still higher flame retardance. Since such an electromagnetic wave suppression body has a structure in which the electromagnetic wave suppression sheet 1 seals the electromagnetic wave suppression material 12 with the moisture-proof films 11a and 11b, the shape can be sufficiently retained. Moreover, since the electromagnetic wave suppression body can maintain the electromagnetic wave suppression function stably and has high flexibility, it can be attached to a structure having a complicated shape such as a flexible printed circuit board.
- an electrolyte, an alcohol, an acrylate monomer, and a crosslinking agent are dissolved in a solvent, a polymerization initiator is added, and the mixture is sufficiently stirred.
- the acrylate monomer may be any monofunctional acrylate such as methyl acrylate, ethyl acrylate, aromatic acrylate, acrylamide, etc.
- acrylamide may be used.
- the crosslinking agent include bifunctional acrylates and trifunctional or higher acrylates.
- N, N′-alkylene bisacrylamide is preferable and N, N′-methylene bisacrylamide is most preferable from the viewpoint of interaction with alcohols and electrolytes.
- a crosslinking method a crosslinking method using both thermal crosslinking and photocrosslinking can be used.
- the polymerization initiator include radical initiators, and azo initiators and peroxide initiators are particularly preferable. Among them, ammonium peroxodisulfate is most preferable from the viewpoint of interaction with alcohols and electrolytes.
- a defoaming process is performed in which the mixed solution after stirring is placed in a vacuum oven depressurized at room temperature, and oxygen is removed from the mixed solution.
- the moisture-proof films 11a and 11b described above are cut into a predetermined size, the sealing surface that is the thermoplastic resin forming surface is faced, and a predetermined temperature is applied with an impact sealer to inject the mixed solution. Laminate three directions other than the entrance to make bags of moisture-proof films 11a and 11b.
- a bag of moisture-proof films 11a and 11b is inserted into a thickness-determining jig, and the mixed solution is injected into the bag and filled. With the impact sealer, while extruding the overflowing mixed solution, the bag inlet of the moisture-proof films 11a and 11b is closed to form a sheet with a predetermined thickness.
- an electromagnetic wave suppression material 12 made of an acrylamide polymer gel is prepared by performing a polymerization reaction and a crosslinking reaction of an acrylate monomer in the sheet.
- the electromagnetic wave suppression sheet 1 is formed.
- Specific examples of acrylamide polymer gels include acrylamide as an acrylate monomer, N, N′-methylenebisacrylamide as a crosslinking agent, ammonium peroxodisulfate as a polymerization initiator, sodium chloride as an electrolyte, and ethylene as an alcohol. Glycol can be used.
- acrylamide is polymerized by ammonium peroxodisulfate, and at the same time, the cross-linking agent N, N′-methylenebisacrylamide is bonded to a part of the side chain of acrylamide to form a cross-link and has a three-dimensional network structure.
- Polyacrylamide is produced. The polyacrylamide absorbs the sodium chloride solution and ethylene glycol and swells to produce a polyacrylamide gel.
- the electromagnetic wave suppression sheet 1 is taken out from the oven, the non-woven fabric 21 that is a tape-like base material is disposed on at least one of the surfaces, and the adhesive 22 is applied or immersed in the non-woven fabric 21 to form the adhesive layer 2. .
- the thickness (t2) ymm of the electromagnetic wave suppression sheet 1 composed of the moisture-proof films 11a and 11b and an acrylate polymer gel containing x mass% of alcohols is expressed in xy coordinates (x, y).
- a point (10, 1.0), b point (10, 3.0), and c point (20, 1.0) are molded into a region formed by connecting the three points. Freezing and high flame retardancy can be obtained.
- the electromagnetic wave suppression function can be exhibited stably without freezing the gel even in a low temperature environment.
- the electromagnetic wave suppressing material 12 when the alcohol is added in the range of 10% by mass to 20% by mass, the electromagnetic wave suppressing material 12 having a gel freezing point of ⁇ 20 ° C. or lower is obtained by adding 3.0 mol / L or more of the electrolyte. be able to. As a result, the electromagnetic wave suppressing material 12 can stably exhibit the electromagnetic wave suppressing function without freezing the gel even in a low temperature environment. For example, in Japan, the electromagnetic wave suppressing material 12 can be used indoors and outdoors throughout the year. . Examples Hereinafter, examples of the present invention will be described. In addition, a various change is possible for a present Example in the range which does not deviate from the summary of this invention.
- ammonium peroxodisulfate (0.04 g, manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator was added, and the mixture was sufficiently stirred with a stirrer until ammonium peroxodisulfate was completely dissolved.
- the concentration of the mixed solution was sodium chloride 2 mol / L, ethylene glycol 20 wt%, acrylamide 1.0 mol / L, N, N′-methylenebisacrylamide 0.5 mol / L, and ammonium peroxodisulfate 0.2 mol / L. became.
- the mixed solution after stirring was placed in a vacuum oven depressurized at room temperature, and defoaming treatment was performed to remove oxygen from the mixed solution.
- the moisture-proof film described above Kureha Co., Ltd. Sereru (thickness of about 0.125 mm) is cut into a predetermined size, with the sealing surface that is the thermoplastic resin forming surface facing each other, with an impact sealer, A predetermined temperature was applied to laminate the three directions other than the mixed solution inlet, and a bag of moisture-proof film was produced.
- the moisture-proof film bag is inserted into a thicknessing jig assembled from a glass substrate and an aluminum plate spacer having a thickness required for the electromagnetic wave suppression sheet, and the mixed solution is injected into the super-moisture-proof film bag. Then fill.
- the impact sealer pushed out the overflowed mixed solution and closed the inlet of the moisture-proof film bag to form an electromagnetic wave suppression sheet.
- a sheet filled with the mixed solution is sandwiched between thickening jigs and placed in an oven set at 60 ° C., and acrylamide polymerization reaction and crosslinking reaction are performed in the sheet to generate a polyacrylamide gel. . Thereby, an electromagnetic wave suppression sheet is manufactured.
- the electromagnetic wave suppression sheet which sealed the electromagnetic wave suppression material from the oven was taken out.
- ⁇ Measurement of freezing point depression of electromagnetic wave suppression material> In the production method described above, the freezing points of 16 types of electromagnetic wave suppression sheets (samples 1 to 16) when the sodium chloride concentration [mol / L] and the ethylene glycol concentration [wt%] were produced were measured. Table 1 shows the values of sodium chloride concentration [mol / L], ethylene glycol concentration [wt%] and freezing point [° C.] in Samples 1 to 16.
- FIG. 3 shows the relationship.
- the freezing point of the polyacrylamide gel decreased as the sodium chloride concentration [mol / L] increased.
- the freezing point of the polyacrylamide gel decreased as the ethylene glycol concentration [wt%] increased.
- the sodium chloride concentration is 1.0 mol / L
- the freezing point of the polyacrylamide gel does not fall below ⁇ 20 ° C. regardless of the ethylene glycol concentration of 10 to 25 wt%.
- Judgment is the sum of the flaming combustion duration after the end of the first and second flame contact, the flaming combustion duration and the non-flame duration after the second flame contact, and the flaming of 5 test pieces Judgment was made based on the total combustion time and the presence or absence of combustion drops (drip).
- the V0 determination was made within 10 seconds for both the first time and the second time, and the V1 and V2 determinations were made when flaming combustion was finished within 20 seconds.
- the sum of the second flammable combustion duration and the flameless combustion time was assumed to have disappeared within 30 seconds for the V0 determination and within 60 seconds for the V1, V2 determination.
- the total of the flammable combustion times of the five test pieces was determined to be within 50 seconds for V0 determination and within 250 seconds for V1, V2 determination.
- the burning fall object is permitted only to V2, and all the test pieces must not be burned out.
- the test piece which consists only of the electromagnetic wave suppression sheet obtained by the manufacturing method mentioned above was burned out. Therefore, a flame test was performed by providing a flame retardant adhesive layer on one side of the test piece.
- a flame retardant adhesive layer a pressure-sensitive double-sided adhesive tape UT1515 (manufactured by Sony Chemical & Information Device Co., Ltd.) having a thickness of about 150 ⁇ m was used.
- This pressure-sensitive double-sided adhesive tape contains Konron I (thickness: about 40 ⁇ m) manufactured by Shin-Fuji Paper Co., Ltd. as a nonwoven fabric, and hexabromobenzene (HBB: C 6 Br 6 ) as a flame retardant 30 to 40% by mass, It contains 5 to 10% by mass of antimony trioxide (Sb 2 O 3 ).
- HBB hexabromobenzene
- Sb 2 O 3 antimony trioxide
- Test piece 2 was produced in the same manner as test piece 1 except that the thickness of the strip-shaped electromagnetic wave suppression sheet was 1.0 mm.
- Test piece 3 was produced in the same manner as the test piece 1 except that the thickness of the strip-shaped electromagnetic wave suppression sheet was 2.0 mm.
- Test piece 4 was produced in the same manner as the test piece 1 except that the thickness of the strip-shaped electromagnetic wave suppression sheet was set to 3.0 mm.
- Test piece 5 was produced in the same manner as test piece 1 except that the ethylene glycol concentration was 20% by mass.
- Test piece 6 A test piece 6 was prepared in the same manner as the test piece 1 except that the ethylene glycol concentration was 20% by mass and the thickness of the strip-shaped electromagnetic wave suppression sheet was 1.0 mm.
- Test piece 7 A test piece 7 was prepared in the same manner as the test piece 1 except that the ethylene glycol concentration was 20% by mass and the thickness of the strip-shaped electromagnetic wave suppression sheet was 2.0 mm.
- Test piece 8 A test piece 8 was produced in the same manner as the test piece 1 except that the ethylene glycol concentration was 20 mass% and the thickness of the strip-shaped electromagnetic wave suppression sheet was 3.0 mm.
- Test piece 9 The test piece except that the ethylene glycol concentration was 20% by mass, the thickness of the strip-shaped electromagnetic wave suppression sheet was 1.0 mm, and the adhesive layer which was made of the same resin as UT1515 and did not contain the base nonwoven fabric was provided. In the same manner as in Example 1, a test piece 9 was produced.
- Test piece 10 The test piece except that the ethylene glycol concentration is 20% by mass, the thickness of the strip-shaped electromagnetic wave suppression sheet is 2.0 mm, the adhesive layer is made of the same resin as that of UT1515 and does not contain the nonwoven fabric of the base material. In the same manner as in Example 1, a test piece 10 was produced.
- Test piece 11 The test piece except that the ethylene glycol concentration is 10% by mass, the thickness of the strip-shaped electromagnetic wave suppression sheet is 3.0 mm, and the adhesive layer is made of the same resin as UT1515 and does not contain the non-woven fabric of the base material.
- a test piece 11 was produced in the same manner as in Example 1. In addition, when the ethylene glycol concentration was 30% by mass, poor curing of the polyacrylamide gel occurred, and an electromagnetic wave suppression sheet having a predetermined thickness could not be produced. Further, a test piece having a thickness of 3.5 mm or more could not be manufactured due to the specification of the actual machine. Table 2 shows the results of the burning test of the test pieces 1 to 8, and Table 3 shows the results of the burning test of the test pieces 9 to 11.
- the flame retardance of the test pieces 2 to 4 and 6 could be determined.
- the test pieces 1 to 4 having an ethylene glycol concentration of 10% by mass it is considered that the test piece 1 having a thickness of 0.5 mm has little moisture due to a small amount of gel and did not exhibit flame retardancy.
- the test pieces 2 to 4 exhibited flame retardancy of V1, V2, and V0, respectively. This is probably because the gel composition has a large amount of water because the thickness is 1.0 mm or more.
- the test pieces 5 to 8 having an ethylene glycol concentration of 20% by mass it is considered that the test piece 5 having a thickness of 0.5 mm has a low water content due to a small amount of gel and does not exhibit flame retardancy. .
- the test piece 6 having a thickness of 1.0 mm exhibited V1 flame retardance, but the test pieces 7 and 8 having a thickness of 2.0 mm or more burned out and did not exhibit flame retardancy. It was. This is presumably because the amount of ethylene glycol contained in the gel composition increased with the increase in thickness. That is, the thickness ymm of the electromagnetic wave suppression sheet composed of a moisture-proof film and a polyacrylate gel containing x mass% ethylene glycol is represented by points a (10, 1.0) and b in xy coordinates (x, y). It is found that high antifreeze and high flame retardancy can be obtained by molding in the region formed by connecting three points (10, 3.0) and c point (20, 1.0). It was.
- test pieces 9 to 11 made of the same resin as UT1515 and provided with an adhesive layer not containing a nonwoven fabric as a base material burned out and did not exhibit flame retardancy.
- the test piece 6 and the test piece 9, or the test piece 4 and the test piece 11 by providing an adhesive layer containing a non-woven fabric and a flame-retardant adhesive, high flame retardancy is achieved. It turns out that it is obtained.
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Abstract
An electromagnetic wave inhibiting sheet (1) comprising a moistureproof film (11a), a moistureproof film (11b), and an acrylate polymer gel containing an x% by mass of an alcohol compound is formed in such a thickness (t2)ymm that, in xy coordinates (x, y), the thickness falls within a region formed by connecting three points, i.e., a point a (10, 1.0), a point b (10, 3.0), and a point c (20, 1.0). According to the above constitution, a high level of nonfreezing properties and a high level of flame retardancy can be realized.
Description
本発明は、電子機器等から発生する電磁波の不要輻射を抑制する電磁波抑制体及びその製造方法に関する。
本出願は、日本国において２００８年４月１４日に出願された日本特許出願番号特願２００８－１０４７５２を基礎として優先権を主張するものであり、この出願を参照することにより，本出願に援用される。 The present invention relates to an electromagnetic wave suppressing body that suppresses unnecessary radiation of electromagnetic waves generated from electronic devices and the like, and a method for manufacturing the same.
This application claims priority based on Japanese Patent Application No. 2008-104752 filed on Apr. 14, 2008 in Japan, and is incorporated herein by reference. Is done.
本出願は、日本国において２００８年４月１４日に出願された日本特許出願番号特願２００８－１０４７５２を基礎として優先権を主張するものであり、この出願を参照することにより，本出願に援用される。 The present invention relates to an electromagnetic wave suppressing body that suppresses unnecessary radiation of electromagnetic waves generated from electronic devices and the like, and a method for manufacturing the same.
This application claims priority based on Japanese Patent Application No. 2008-104752 filed on Apr. 14, 2008 in Japan, and is incorporated herein by reference. Is done.
近年、電子機器等から発生する電磁波の不要輻射が問題となっている。特に、高周波数の電磁波の利用の増加に伴って、電磁波ノイズ（干渉）による機器の誤作動や、脳、人体への悪影響といった被害、障害等が新たな環境問題として提起されている。
このような電磁干渉（ＥＭＩ：Electromagnetic Interference）の問題に対処するために、個々の電子機器において、他の機器の正常な作動を妨害するような不要な電磁波の放射を抑制することや、外部から進入する電磁波に対して影響を受けることがない程度まで耐力を向上させることによって、相互の影響を十分に低減乃至回避できる構成とすることが要求されている。
電磁波抑制体（電磁波吸収体）における電磁波吸収の原理は、入射した電磁波エネルギーのほとんどを電磁波抑制体の内部で熱エネルギーに変換するというものである。よって、電磁波抑制体では、その前方に反射するエネルギーと後方へ透過するエネルギーの双方を低減することができる。
電磁波の熱エネルギーへの変換メカニズムは、主に、導電損失、誘電損失、磁性損失に分類され、これら３種類の損失により、電磁波の熱エネルギーへの変換量（電波吸収量）が想定される。このとき、単位体積あたりの電磁波吸収エネルギーＰ［Ｗ／ｍ３］は、電界Ｅ、磁界Ｈ及び周波数ｆを用いて、数式（１）のように表される。 In recent years, unnecessary radiation of electromagnetic waves generated from electronic devices has become a problem. In particular, as the use of high-frequency electromagnetic waves increases, damages such as malfunctions of devices due to electromagnetic noise (interference), adverse effects on the brain and human body, obstacles, and the like have been raised as new environmental problems.
In order to deal with such electromagnetic interference (EMI) problems, individual electronic devices can suppress the emission of unnecessary electromagnetic waves that interfere with the normal operation of other devices, There is a demand for a structure that can sufficiently reduce or avoid the mutual influence by improving the proof stress to such an extent that it is not affected by the electromagnetic waves that enter.
The principle of electromagnetic wave absorption in the electromagnetic wave suppression body (electromagnetic wave absorber) is that most of the incident electromagnetic wave energy is converted into thermal energy inside the electromagnetic wave suppression body. Therefore, in the electromagnetic wave suppression body, it is possible to reduce both the energy reflected forward and the energy transmitted backward.
The conversion mechanism of electromagnetic waves into thermal energy is mainly classified into conductive loss, dielectric loss, and magnetic loss, and the amount of conversion of electromagnetic waves into thermal energy (radio wave absorption amount) is assumed by these three types of losses. At this time, the electromagnetic wave absorption energy P [W / m 3 ] per unit volume is expressed as Equation (1) using the electric field E, the magnetic field H, and the frequency f.
このような電磁干渉（ＥＭＩ：Electromagnetic Interference）の問題に対処するために、個々の電子機器において、他の機器の正常な作動を妨害するような不要な電磁波の放射を抑制することや、外部から進入する電磁波に対して影響を受けることがない程度まで耐力を向上させることによって、相互の影響を十分に低減乃至回避できる構成とすることが要求されている。
電磁波抑制体（電磁波吸収体）における電磁波吸収の原理は、入射した電磁波エネルギーのほとんどを電磁波抑制体の内部で熱エネルギーに変換するというものである。よって、電磁波抑制体では、その前方に反射するエネルギーと後方へ透過するエネルギーの双方を低減することができる。
電磁波の熱エネルギーへの変換メカニズムは、主に、導電損失、誘電損失、磁性損失に分類され、これら３種類の損失により、電磁波の熱エネルギーへの変換量（電波吸収量）が想定される。このとき、単位体積あたりの電磁波吸収エネルギーＰ［Ｗ／ｍ３］は、電界Ｅ、磁界Ｈ及び周波数ｆを用いて、数式（１）のように表される。 In recent years, unnecessary radiation of electromagnetic waves generated from electronic devices has become a problem. In particular, as the use of high-frequency electromagnetic waves increases, damages such as malfunctions of devices due to electromagnetic noise (interference), adverse effects on the brain and human body, obstacles, and the like have been raised as new environmental problems.
In order to deal with such electromagnetic interference (EMI) problems, individual electronic devices can suppress the emission of unnecessary electromagnetic waves that interfere with the normal operation of other devices, There is a demand for a structure that can sufficiently reduce or avoid the mutual influence by improving the proof stress to such an extent that it is not affected by the electromagnetic waves that enter.
The principle of electromagnetic wave absorption in the electromagnetic wave suppression body (electromagnetic wave absorber) is that most of the incident electromagnetic wave energy is converted into thermal energy inside the electromagnetic wave suppression body. Therefore, in the electromagnetic wave suppression body, it is possible to reduce both the energy reflected forward and the energy transmitted backward.
The conversion mechanism of electromagnetic waves into thermal energy is mainly classified into conductive loss, dielectric loss, and magnetic loss, and the amount of conversion of electromagnetic waves into thermal energy (radio wave absorption amount) is assumed by these three types of losses. At this time, the electromagnetic wave absorption energy P [W / m 3 ] per unit volume is expressed as Equation (1) using the electric field E, the magnetic field H, and the frequency f.
このような電磁波抑制体の一つとして、現在、磁性シートが主に電子機器に利用され、特に、プリント回路基板上、フレキシブルプリント回路（ＦＰＣ：Flexible Printed Circuits）上、パッケージ上面等に貼り付けて利用されている。磁性シートは、フェライトや金属磁性粉末を樹脂と混合した材料をはじめとして、カーボン系の材料を含有させたもの等、様々な種類のものが開発されている。
この磁性シートの使い方には、主に２通りの使い方がある。一つは、アンテナ源から輻射された電磁波を吸収する使い方であり、もうひとつは、アンテナ源に高調波ノイズ成分が乗ることを未然に抑制する高調波フィルタとしての使い方である。
しかし、磁性シートは、光透過性（透明性）が低いことから、例えば建造物の窓等に用いて、透明部材による構造を通じて室内に飛来する電磁波の低減に寄与させることが難しいのが現状である。
そこで、最近ではＮａＣｌを含有するゲル組成物が透明性を有しつつ、かつ電磁波抑制体として機能することから、注目を集めている（例えば特許文献１参照。）。ＮａＣｌのゲル電解質は、高い誘電損失を有することから、ＭＨｚ帯域、ＧＨｚ帯域において高い電磁波吸収率が期待されている。
As one of such electromagnetic wave suppressors, at present, magnetic sheets are mainly used for electronic devices, and in particular, affixed on printed circuit boards, flexible printed circuits (FPCs), upper surfaces of packages, and the like. It's being used. Various types of magnetic sheets have been developed, including a material in which a ferrite material or a metal magnetic powder is mixed with a resin and a carbon-based material.
There are mainly two ways to use this magnetic sheet. One is a method of absorbing electromagnetic waves radiated from the antenna source, and the other is a method of using as a harmonic filter that suppresses the presence of harmonic noise components on the antenna source.
However, since the magnetic sheet has low light transmittance (transparency), it is difficult to contribute to the reduction of electromagnetic waves that fly into the room through the structure of the transparent member, for example, for windows of buildings. is there.
Thus, recently, a gel composition containing NaCl has attracted attention because it has transparency and functions as an electromagnetic wave suppressor (see, for example, Patent Document 1). Since the NaCl gel electrolyte has a high dielectric loss, a high electromagnetic wave absorption rate is expected in the MHz band and the GHz band.
ところで、電子機器は、寒冷地、冷凍室等の低温環境においても使用されている。このため、電磁波抑制体としてゲル組成物を電子機器に用いた場合、氷点下でゲルの水分が凍結してゲル組成物の誘電率が低下し、電磁波抑制機能が発揮されないことがあった。
また、電磁波抑制体は、内部で電磁波を熱エネルギーに変換することから、高い難燃性が望まれていた。
本発明は、このような従来の実情に鑑みて提案されたものであり、高い不凍性と高い難燃性を有する電磁波抑制体及びその製造方法を提供する。
本件発明者は、上述の課題を解決するために鋭意研究を重ねた結果、アクリレート系高分子ゲルを有する電磁波抑制シートにおいて、アクリレート系高分子ゲルのアルコール類の濃度及び電磁波抑制シートの厚さを規定することにより、高い不凍性と高い難燃性が得られることを見出した。
すなわち、本発明に係る電磁波抑制体は、第１の防湿フィルムと、第２の防湿フィルムと、前記第１の防湿フィルムと前記第２の防湿フィルムとの間に封止されるアクリレート系高分子ゲルとからなる電磁波抑制シートを有し、前記アクリレート系高分子ゲルが、ｘ質量％のアルコール類を含有し、前記電磁波抑制シートの厚さｙｍｍが、ｘｙ座標（ｘ，ｙ）において、ａ点（１０，１．０）、ｂ点（１０，３．０）、及びｃ点（２０，１．０）の３点を結んで形成される領域内にあることを特徴としている。
また、本発明に係る電磁波抑制体の製造方法は、第１の防湿フィルムと第２の防湿フィルムとの間に、ｘ質量％のアルコール類と、アクリレート系モノマーと、重合開始剤とを含有する組成物を注入して密閉し、前記第１の防湿フィルムと、前記第２の防湿フィルムと、前記組成物がゲル化したアクリレート系高分子ゲルとからなる電磁波抑制シートの厚さｙｍｍを、ｘｙ座標（ｘ，ｙ）において、ａ点（１０，１．０）、ｂ点（１０，３．０）、及びｃ点（２０，１．０）の３点を結んで形成される領域内に成型することを特徴としている。
本発明によれば、アクリレート系高分子ゲルのアルコール類の濃度、及びこのアクリレート系高分子ゲルを有する電磁波抑制シートの厚さを所定範囲に規定することより、高い不凍性と高い難燃性を得ることができる。 Incidentally, electronic devices are also used in low-temperature environments such as cold districts and freezer rooms. For this reason, when a gel composition is used for an electronic device as an electromagnetic wave suppressor, the moisture of the gel is frozen below freezing point, the dielectric constant of the gel composition is lowered, and the electromagnetic wave suppression function may not be exhibited.
Moreover, since the electromagnetic wave suppression body converts electromagnetic waves into heat energy inside, high flame retardancy has been desired.
This invention is proposed in view of such a conventional situation, and provides the electromagnetic wave suppression body which has high antifreezing property and high flame retardance, and its manufacturing method.
As a result of intensive research in order to solve the above-mentioned problems, the inventors of the present invention have determined the alcohol concentration of the acrylate polymer gel and the thickness of the electromagnetic wave suppression sheet in the electromagnetic wave suppression sheet having the acrylate polymer gel. It has been found that high antifreeze and high flame retardancy can be obtained by prescribing.
That is, the electromagnetic wave suppressing body according to the present invention includes a first moisture-proof film, a second moisture-proof film, and an acrylate polymer sealed between the first moisture-proof film and the second moisture-proof film. The acrylate polymer gel contains x% by mass of alcohol, and the thickness ymm of the electromagnetic wave suppression sheet is point a in the xy coordinates (x, y). It is characterized by being in a region formed by connecting three points of (10, 1.0), b point (10, 3.0), and c point (20, 1.0).
Moreover, the manufacturing method of the electromagnetic wave suppression body which concerns on this invention contains alcohol of x mass%, an acrylate-type monomer, and a polymerization initiator between the 1st moisture-proof film and the 2nd moisture-proof film. The composition is injected and sealed, and the thickness ymm of the electromagnetic wave suppression sheet composed of the first moisture-proof film, the second moisture-proof film, and the acrylate polymer gel in which the composition is gelled is expressed as xy. In the coordinate (x, y), within the region formed by connecting the three points of point a (10, 1.0), point b (10, 3.0), and point c (20, 1.0) It is characterized by molding.
According to the present invention, by specifying the alcohol concentration of the acrylate polymer gel and the thickness of the electromagnetic wave suppression sheet having the acrylate polymer gel within a predetermined range, high antifreeze and high flame retardancy are achieved. Can be obtained.
また、電磁波抑制体は、内部で電磁波を熱エネルギーに変換することから、高い難燃性が望まれていた。
本発明は、このような従来の実情に鑑みて提案されたものであり、高い不凍性と高い難燃性を有する電磁波抑制体及びその製造方法を提供する。
本件発明者は、上述の課題を解決するために鋭意研究を重ねた結果、アクリレート系高分子ゲルを有する電磁波抑制シートにおいて、アクリレート系高分子ゲルのアルコール類の濃度及び電磁波抑制シートの厚さを規定することにより、高い不凍性と高い難燃性が得られることを見出した。
すなわち、本発明に係る電磁波抑制体は、第１の防湿フィルムと、第２の防湿フィルムと、前記第１の防湿フィルムと前記第２の防湿フィルムとの間に封止されるアクリレート系高分子ゲルとからなる電磁波抑制シートを有し、前記アクリレート系高分子ゲルが、ｘ質量％のアルコール類を含有し、前記電磁波抑制シートの厚さｙｍｍが、ｘｙ座標（ｘ，ｙ）において、ａ点（１０，１．０）、ｂ点（１０，３．０）、及びｃ点（２０，１．０）の３点を結んで形成される領域内にあることを特徴としている。
また、本発明に係る電磁波抑制体の製造方法は、第１の防湿フィルムと第２の防湿フィルムとの間に、ｘ質量％のアルコール類と、アクリレート系モノマーと、重合開始剤とを含有する組成物を注入して密閉し、前記第１の防湿フィルムと、前記第２の防湿フィルムと、前記組成物がゲル化したアクリレート系高分子ゲルとからなる電磁波抑制シートの厚さｙｍｍを、ｘｙ座標（ｘ，ｙ）において、ａ点（１０，１．０）、ｂ点（１０，３．０）、及びｃ点（２０，１．０）の３点を結んで形成される領域内に成型することを特徴としている。
本発明によれば、アクリレート系高分子ゲルのアルコール類の濃度、及びこのアクリレート系高分子ゲルを有する電磁波抑制シートの厚さを所定範囲に規定することより、高い不凍性と高い難燃性を得ることができる。 Incidentally, electronic devices are also used in low-temperature environments such as cold districts and freezer rooms. For this reason, when a gel composition is used for an electronic device as an electromagnetic wave suppressor, the moisture of the gel is frozen below freezing point, the dielectric constant of the gel composition is lowered, and the electromagnetic wave suppression function may not be exhibited.
Moreover, since the electromagnetic wave suppression body converts electromagnetic waves into heat energy inside, high flame retardancy has been desired.
This invention is proposed in view of such a conventional situation, and provides the electromagnetic wave suppression body which has high antifreezing property and high flame retardance, and its manufacturing method.
As a result of intensive research in order to solve the above-mentioned problems, the inventors of the present invention have determined the alcohol concentration of the acrylate polymer gel and the thickness of the electromagnetic wave suppression sheet in the electromagnetic wave suppression sheet having the acrylate polymer gel. It has been found that high antifreeze and high flame retardancy can be obtained by prescribing.
That is, the electromagnetic wave suppressing body according to the present invention includes a first moisture-proof film, a second moisture-proof film, and an acrylate polymer sealed between the first moisture-proof film and the second moisture-proof film. The acrylate polymer gel contains x% by mass of alcohol, and the thickness ymm of the electromagnetic wave suppression sheet is point a in the xy coordinates (x, y). It is characterized by being in a region formed by connecting three points of (10, 1.0), b point (10, 3.0), and c point (20, 1.0).
Moreover, the manufacturing method of the electromagnetic wave suppression body which concerns on this invention contains alcohol of x mass%, an acrylate-type monomer, and a polymerization initiator between the 1st moisture-proof film and the 2nd moisture-proof film. The composition is injected and sealed, and the thickness ymm of the electromagnetic wave suppression sheet composed of the first moisture-proof film, the second moisture-proof film, and the acrylate polymer gel in which the composition is gelled is expressed as xy. In the coordinate (x, y), within the region formed by connecting the three points of point a (10, 1.0), point b (10, 3.0), and point c (20, 1.0) It is characterized by molding.
According to the present invention, by specifying the alcohol concentration of the acrylate polymer gel and the thickness of the electromagnetic wave suppression sheet having the acrylate polymer gel within a predetermined range, high antifreeze and high flame retardancy are achieved. Can be obtained.
以下、本発明を適用した具体的な実施の形態について、図面を参照しながら詳細に説明する。
図１は、本実施の形態における電磁波抑制体の断面図である。この電磁波抑制体は、防湿フィルム１１ａ，１１ｂの間に電磁波抑制材料１２が封止されて構成される電磁波抑制シート１を有する。すなわち、電磁波抑制シート１は、防湿フィルム１１ａ，１１ｂの厚さｔ１と電磁波抑制材料１２の厚さとが加算される厚さｔ２を有する。なお、防湿フィルム１１ａ，１１ｂの厚さｔ１は、０．０５～０．２ｍｍ程度である。
防湿フィルム１１ａ，１１ｂは、優れた防湿性を有し、電磁波抑制材料の水分が蒸発するのを防止する。防湿フィルム１１ａ，１１ｂは、例えば、金属酸化物等の透湿防止用バリア層が形成されたＰＥＴ（polyethylene terephthalate）フィルムを熱可塑性樹脂にて複数枚ラミネートし、最表面である封止面に封止用熱可塑性樹脂を形成したものである。このような防湿フィルム１１ａ，１１ｂの一例として、株式会社クレハ製セレール（商標）が挙げられる。
電磁波抑制材料１２は、アルコール類と、電解質とを含有するアクリレート系高分子ゲルからなる。このゲル化合物は、アルコール類と電解質とを含有するため、ゲルの凍結点が降下し、低温環境においても電磁波抑制機能が安定的に維持される。
アルコール類は、不凍液として作用するものが用いられる。例えば、１級アルコール、２級アルコール、３級以上のアルコール類が挙げられる。具体的には、メタノール、エタノール、プロパノール、ブタノール、エチレングリコール（ＥＧ）、プロピレングリコール（ＰＧ）、ペンタエリスリトール等が挙げられ、その中でも、機能発現及び他の化合物との相互作用の観点から、グリコール類、特にエチレングリコールが最も好ましい。
電解質は、溶液の凝固点降下を引き起こすものが用いられる。例えば、高誘電率の極性溶媒に高い溶解度を有するものが挙げられる。上述の数式（１）中の誘電損失である第２項の誘電率ε’’が高い材料は、ＭＨｚ帯域、ＧＨｚ帯域の高周波数帯域において電磁波を効率的に吸収、抑制するため、電解質溶液をゲルに含有させることにより、高周波数帯域における電磁波吸収効率を高めることができる。
図２は、硝酸ナトリウム、硝酸カリウム、塩化カリウム、塩化ナトリウムの水への溶解度を示すグラフである。このグラフは、溶媒１００ｇに溶ける溶質の質量をグラム単位で表した数値で示したものである。この４種類の物質のうち、塩化カリウム及び塩化ナトリウムは、溶解度曲線の勾配が小さく、多少の温度変化でも結晶が析出する可能性が少ないため、イオンが安定的に維持される。
このような電解質としては、溶液中で完全にイオンに解離する強電解質であることが好ましく、例えば、塩化ナトリウム、塩化カリウム、塩化カルシウム、酢酸カリウム、酢酸カルシウム等が挙げられる。なお、酢酸カルシウムは保水性、拡散性を有するグリセリンとともに用いることにより電磁波抑制機能を持続的に維持することが可能となる。
アクリレート系高分子ゲルは、アクリレート系モノマーに重合開始剤及び架橋剤が添加されて得られる三次元の網目構造を有している。この三次元の網目構造は、重合開始剤がアクリレート系モノマー同士の連鎖反応を開始させ、架橋剤がアクリレート系高分子の側鎖の一部と連結する架橋の役割を果たすことにより形成されたものである。
このような電磁波抑制シート１において、アクリレート系高分子ゲルが、ｘ質量％のアルコール類を含有し、電磁波抑制シート１の厚さ（ｔ２）ｙｍｍが、ｘｙ座標（ｘ，ｙ）において、ａ点（１０，１．０）、ｂ点（１０，３．０）、及びｃ点（２０，１．０）の３点を結んで形成される領域内にあることが望ましい。これにより電磁波抑制シート１は、高い不凍性と高い難燃性を有することとなる。
また、本実施の形態における電磁波抑制体は、電磁波抑制シート１の少なくとも一方の面上に接着剤層２を有する。すなわち、接着剤層２は、防湿フィルム１１ａ，１１ｂの少なくとも一方に配される。
接着剤層２は、基材である不織布２１と、接着剤２２とを有する。また、電磁波抑制シート１と反対側の接着剤層２上には、剥離用ＰＥＴ（polyethylene terephthalate）が貼着される。そして、使用時にこれを剥離し、電磁波が発生する部位に接着剤層２を貼り付けることにより、電子機器に電磁波抑制体が搭載される。なお、接着剤層２の厚さは、１００μｍ～２００μｍ程度である。
不織布２１は、複数の原料を組み合わせたり、繊維長や太さなどの形状を調整したりすることで目的・用途に応じた機能を持たせることができる。これらの原料としては、例えば、アラミド繊維、ガラス繊維、セルロース繊維、ナイロン繊維、ビニロン繊維、ポリエステル繊維、ポリオレフィン繊維等を挙げることができる。
接着剤２２は、不織布２１からなるテープ状基材に塗布又は浸漬可能な粘着剤である。接着剤２２は、圧力が加えられることで被着材に対する流動性を持ち、また、剥離に対する凝集性を持つ。このような接着剤２２として、アクリル樹脂系樹脂が挙げられる。例えば、アクリル酸エステルモノマーを極性の高いモノマーと共重合させて接着剤を合成し、これをティッシュペーパー（不織布）に塗布すれば、両面テープを得ることができる。
また、接着剤２２は、難燃剤としてヘキサブロモベンゼン、三酸化アンチモン等を含有することが好ましい。これにより電磁波抑制体は、さらに高い難燃性を有することとなる。
このような電磁波抑制体は、電磁波抑制シート１が防湿フィルム１１ａ，１１ｂにより電磁波抑制材料１２を封止した構造であるため、その形状を十分に保持することができる。また、電磁波抑制体は、電磁波抑制機能を安定的に維持できる上、高い柔軟性を有するため、フレキシブルプリント基板等の複雑な形状の構造体に貼り付けることができる。
次に、本実施の形態における電磁波抑制体の製造方法について説明する。先ず、電解質、アルコール類、アクリレート系モノマー、架橋剤を溶媒に溶解させ、重合開始剤を入れて十分に攪拌する。
ここで、アクリレート系モノマーとしては、メチルアクリレート、エチルアクリレート、芳香族アクリレート、アクリルアミド等、１官能アクリレートであれば何れのものでもよく、特に、アルコール類や電解質との相互作用の観点から、アクリルアミドが最も好ましい。
また、架橋剤としては、例えば、２官能アクリレート、３官能以上のアクリレートが挙げられる。その中でも、アルコール類や電解質との相互作用の観点から、Ｎ，Ｎ’－アルキレンビスアクリルアミドが好ましく、Ｎ，Ｎ’－メチレンビスアクリルアミドが最も好ましい。また、架橋方法としては、熱架橋と光架橋とを併用した架橋方法を用いることが可能である。
また、重合開始剤としては、例えばラジカル開始剤が挙げられ、特に、アゾ系開始剤、過酸化物系開始剤が好ましい。その中でも、アルコール類や電解質との相互作用の観点から、ペルオキソ二硫酸アンモニウムが最も好ましい。
次に、常温で減圧した真空オーブン内に攪拌後の混合溶液を入れ、混合溶液内の酸素を抜く脱泡処理を行う。
次に、上述した防湿フィルム１１ａ，１１ｂを所定のサイズにカットし、熱可塑性樹脂形成面である封止面を向かい合わせにして、インパクトシーラにて、所定の温度を加えて、混合溶液の注入口以外の３方向をラミネートし、防湿フィルム１１ａ，１１ｂの袋を作製する。
次に、厚み出し治具に防湿フィルム１１ａ，１１ｂの袋を差し込み、この袋の中に混合溶液を注入して充填する。インパクトシーラにより、溢れ出た混合溶液を押し出しながら防湿フィルム１１ａ，１１ｂの袋の注入口を閉じて所定の厚さのシート形状にする。
次に、厚み出し治具に挟まれた所定の厚さのシートをオーブンに入れ、シート内でアクリレート系モノマーの重合反応及び架橋反応を行わせてアクリルアミド系高分子ゲルからなる電磁波抑制材料１２を生成し、電磁波抑制シート１を成型する。
具体的なアクリルアミド系高分子ゲルの一例として、アクリレート系モノマーとしてアクリルアミド、架橋剤としてＮ，Ｎ’－メチレンビスアクリルアミド、重合開始剤としてペルオキソ二硫酸アンモニウム、さらには、電解質として塩化ナトリウム、アルコール類としてエチレングリコールを用いることができる。この場合、ペルオキソ二硫酸アンモニウムによりアクリルアミドが重合され、これとともに、架橋剤のＮ，Ｎ’－メチレンビスアクリルアミドがアクリルアミドの一部の側鎖に結合して架橋を形成し、三次元の網目構造を有するポリアクリルアミドが生成される。そして、このポリアクリルアミドが塩化ナトリウム溶液及びエチレングリコールを吸収して膨潤することによりポリアクリルアミドゲルが生成される。
次に、オーブンから電磁波抑制シート１を取り出し、テープ状基材である不織布２１を少なくともどちらか一方の面に配し、接着剤２２を不織布２１に塗布又は浸漬させ、接着剤層２を形成する。そして、接着剤層２上に剥離用ＰＥＴを貼着し、電磁波抑制体を得る。
本実施の形態では、防湿フィルム１１ａ，１１ｂとｘ質量％のアルコール類を含有するアクリレート系高分子ゲルとからなる電磁波抑制シート１の厚さ（ｔ２）ｙｍｍを、ｘｙ座標（ｘ，ｙ）において、ａ点（１０，１．０）、ｂ点（１０，３．０）、及びｃ点（２０，１．０）の３点を結んで形成される領域内に成型することにより、高い不凍性と高い難燃性を得ることができる。
また、電解質及びアルコール類の添加量を調整することにより、低温環境においてもゲルを凍結させずに安定的に電磁波抑制機能を発揮させることができる。特に、アルコール類を１０質量％以上２０質量％以下の範囲で添加する場合において、電解質を３．０ｍｏｌ／Ｌ以上添加することにより、ゲルの凍結点が－２０℃以下の電磁波抑制材料１２を得ることができる。これにより、電磁波抑制材料１２は、低温環境においてもゲルが凍結せずに安定的に電磁波抑制機能を発揮でき、例えば日本国内では、一年を通じて屋内、屋外問わずほとんどの場所でも使用可能となる。
実施例
以下、本発明の実施例について説明する。なお、本実施例は、本発明の要旨を逸脱しない範囲で種々の変更が可能である。
＜電磁波抑制シートの製造＞
以下、電磁波抑制材料を防湿フィルムにより封止した電磁波抑制シートの製造方法について説明する。
純水（６８．６２ｇ）に塩化ナトリウム（８．０１ｇ、関東化学（株）社製）、エチレングリコール（１７．１６ｇ、関東化学（株）社製）、アクリルアミド（６．１０ｇ、和光純薬工業（株）社製）、Ｎ－Ｎ’－メチレンビスアクリルアミド（０．０７ｇ、和光純薬工業（株）社製）を配合し、完全に溶解するまでスターラで攪拌した。次に重合開始剤のペルオキソ二硫酸アンモニウム（０．０４ｇ、和光純薬工業（株）社製）を加え、ペルオキソ二硫酸アンモニウムが完全に溶解するまでスターラで十分攪拌した。
その結果、混合溶液の濃度は、 塩化ナトリウム ２ｍｏｌ／Ｌ、 エチレングリコール ２０ｗｔ％、 アクリルアミド １．０ｍｏｌ／Ｌ、 Ｎ，Ｎ’－メチレンビスアクリルアミド ０．５ｍｏｌ／Ｌ、 ペルオキソ二硫酸アンモニウム ０．２ｍｏｌ／Ｌとなった。
次に、常温で減圧した真空オーブン内に攪拌後の混合溶液を入れ、混合溶液内の酸素を抜く脱泡処理を行った。
次に、上述した防湿フィルムとして株式会社クレハ製セレール（厚さ約０．１２５ｍｍ）を所定のサイズにカットし、熱可塑性樹脂形成面である封止面を向かい合わせにして、インパクトシーラにて、所定の温度を加えて、混合溶液の注入口以外の３方向をラミネートし、防湿フィルムの袋を作製した。
次に、ガラス基板と電磁波抑制シートに必要な厚さを有するアルミ板のスペーサとから組み立てられた厚み出し治具に防湿フィルムの袋を差し込み、この超防湿フィルムの袋の中に混合溶液を注入して充填する。インパクトシーラにより、溢れ出た混合溶液を押し出しながら防湿フィルムの袋の注入口を閉じて電磁波抑制シートの形状にした。
続いて、厚み出し治具に混合溶液が充填されたシートを挟み、これを６０℃に設定されたオーブンに入れ、シート中でアクリルアミドの重合反応及び架橋反応を行わせてポリアクリルアミドゲルを生成させる。これにより電磁波抑制シートが製造される。オーブンから電磁波抑制材料を封止した電磁波抑制シートを取り出した。
＜電磁波抑制材料の凍結点降下測定＞
上述の製造方法において、塩化ナトリウム濃度〔ｍｏｌ／Ｌ〕及びエチレングリコール濃度〔ｗｔ％〕を変えて製造した場合の１６種類の電磁波抑制シート（サンプル１～１６）の凍結点を測定した。サンプル１～１６における塩化ナトリウム濃度〔ｍｏｌ／Ｌ〕、エチレングリコール濃度〔ｗｔ％〕及び凍結点〔℃〕の値を表１に示す。 Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view of an electromagnetic wave suppressing body in the present embodiment. This electromagnetic wave suppression body has the electromagneticwave suppression sheet 1 comprised by sealing the electromagnetic wave suppression material 12 between the moisture- proof films 11a and 11b. That is, the electromagnetic wave suppression sheet 1 has a thickness t2 in which the thickness t1 of the moisture- proof films 11a and 11b and the thickness of the electromagnetic wave suppression material 12 are added. The moistureproof films 11a and 11b have a thickness t1 of about 0.05 to 0.2 mm.
The moisture- proof films 11a and 11b have excellent moisture-proof properties and prevent the moisture of the electromagnetic wave suppressing material from evaporating. The moisture- proof films 11a and 11b are formed by laminating a plurality of PET (polyethylene terephthalate) films with a barrier layer for preventing moisture permeation, such as metal oxide, with a thermoplastic resin, and sealing the sealing surface on the outermost surface. A thermoplastic resin for stopping is formed. As an example of such moisture- proof films 11a and 11b, Kerrha Co., Ltd. Serer (trademark) is mentioned.
The electromagneticwave suppression material 12 is made of an acrylate polymer gel containing alcohols and an electrolyte. Since this gel compound contains alcohols and an electrolyte, the freezing point of the gel is lowered and the electromagnetic wave suppression function is stably maintained even in a low temperature environment.
Alcohols that act as antifreeze are used. For example, primary alcohols, secondary alcohols, tertiary alcohols and higher are listed. Specific examples include methanol, ethanol, propanol, butanol, ethylene glycol (EG), propylene glycol (PG), pentaerythritol and the like. Among these, glycols are used from the viewpoint of functional expression and interaction with other compounds. Most preferred are ethylene glycol.
An electrolyte that causes a freezing point depression of the solution is used. For example, those having high solubility in a polar solvent having a high dielectric constant can be mentioned. The material having a high dielectric constant ε ″ of the second term, which is the dielectric loss in the above-described formula (1), uses an electrolyte solution in order to efficiently absorb and suppress electromagnetic waves in the high frequency band of MHz band and GHz band. Inclusion in the gel can increase the electromagnetic wave absorption efficiency in the high frequency band.
FIG. 2 is a graph showing the solubility of sodium nitrate, potassium nitrate, potassium chloride, and sodium chloride in water. This graph shows the mass of a solute dissolved in 100 g of solvent as a numerical value expressed in grams. Of these four types of substances, potassium chloride and sodium chloride have a low solubility curve gradient and are less likely to precipitate crystals even with a slight temperature change, so that ions are stably maintained.
Such an electrolyte is preferably a strong electrolyte that dissociates completely into ions in a solution, and examples thereof include sodium chloride, potassium chloride, calcium chloride, potassium acetate, and calcium acetate. In addition, it becomes possible to maintain an electromagnetic wave suppression function continuously by using calcium acetate with glycerin having water retention and diffusibility.
The acrylate polymer gel has a three-dimensional network structure obtained by adding a polymerization initiator and a crosslinking agent to an acrylate monomer. This three-dimensional network structure is formed by a polymerization initiator that initiates a chain reaction between acrylate monomers, and a crosslinking agent that acts as a crosslink that links some of the side chains of the acrylate polymer. It is.
In such an electromagneticwave suppression sheet 1, the acrylate polymer gel contains x mass% alcohol, and the thickness (t2) ymm of the electromagnetic wave suppression sheet 1 is point a in the xy coordinates (x, y). It is desirable to be within a region formed by connecting three points of (10, 1.0), b point (10, 3.0), and c point (20, 1.0). Thereby, the electromagnetic wave suppression sheet 1 has high antifreeze and high flame retardance.
Moreover, the electromagnetic wave suppression body in the present exemplary embodiment has theadhesive layer 2 on at least one surface of the electromagnetic wave suppression sheet 1. That is, the adhesive layer 2 is disposed on at least one of the moisture- proof films 11a and 11b.
Theadhesive layer 2 includes a nonwoven fabric 21 that is a base material and an adhesive 22. Moreover, PET (polyethylene terephthalate) for peeling is stuck on the adhesive layer 2 on the side opposite to the electromagnetic wave suppression sheet 1. And this is peeled at the time of use, and the electromagnetic wave suppression body is mounted in an electronic device by sticking the adhesive bond layer 2 to the site | part which electromagnetic waves generate | occur | produce. The adhesive layer 2 has a thickness of about 100 μm to 200 μm.
Thenonwoven fabric 21 can have a function according to the purpose and application by combining a plurality of raw materials or adjusting the shape such as fiber length and thickness. Examples of these raw materials include aramid fibers, glass fibers, cellulose fibers, nylon fibers, vinylon fibers, polyester fibers, and polyolefin fibers.
The adhesive 22 is a pressure-sensitive adhesive that can be applied to or immersed in a tape-shaped substrate made of thenonwoven fabric 21. The adhesive 22 has fluidity with respect to the adherend when pressure is applied, and also has cohesiveness with respect to peeling. Examples of such an adhesive 22 include acrylic resin-based resins. For example, a double-sided tape can be obtained by synthesizing an acrylate monomer with a highly polar monomer to synthesize an adhesive and applying it to tissue paper (nonwoven fabric).
The adhesive 22 preferably contains hexabromobenzene, antimony trioxide or the like as a flame retardant. Thereby, an electromagnetic wave suppression body will have a still higher flame retardance.
Since such an electromagnetic wave suppression body has a structure in which the electromagneticwave suppression sheet 1 seals the electromagnetic wave suppression material 12 with the moisture- proof films 11a and 11b, the shape can be sufficiently retained. Moreover, since the electromagnetic wave suppression body can maintain the electromagnetic wave suppression function stably and has high flexibility, it can be attached to a structure having a complicated shape such as a flexible printed circuit board.
Next, the manufacturing method of the electromagnetic wave suppression body in this Embodiment is demonstrated. First, an electrolyte, an alcohol, an acrylate monomer, and a crosslinking agent are dissolved in a solvent, a polymerization initiator is added, and the mixture is sufficiently stirred.
Here, the acrylate monomer may be any monofunctional acrylate such as methyl acrylate, ethyl acrylate, aromatic acrylate, acrylamide, etc. In particular, from the viewpoint of interaction with alcohols and electrolytes, acrylamide may be used. Most preferred.
Examples of the crosslinking agent include bifunctional acrylates and trifunctional or higher acrylates. Among these, N, N′-alkylene bisacrylamide is preferable and N, N′-methylene bisacrylamide is most preferable from the viewpoint of interaction with alcohols and electrolytes. As a crosslinking method, a crosslinking method using both thermal crosslinking and photocrosslinking can be used.
Examples of the polymerization initiator include radical initiators, and azo initiators and peroxide initiators are particularly preferable. Among them, ammonium peroxodisulfate is most preferable from the viewpoint of interaction with alcohols and electrolytes.
Next, a defoaming process is performed in which the mixed solution after stirring is placed in a vacuum oven depressurized at room temperature, and oxygen is removed from the mixed solution.
Next, the moisture- proof films 11a and 11b described above are cut into a predetermined size, the sealing surface that is the thermoplastic resin forming surface is faced, and a predetermined temperature is applied with an impact sealer to inject the mixed solution. Laminate three directions other than the entrance to make bags of moisture- proof films 11a and 11b.
Next, a bag of moisture- proof films 11a and 11b is inserted into a thickness-determining jig, and the mixed solution is injected into the bag and filled. With the impact sealer, while extruding the overflowing mixed solution, the bag inlet of the moisture- proof films 11a and 11b is closed to form a sheet with a predetermined thickness.
Next, a sheet having a predetermined thickness sandwiched between thickness-thickening jigs is put in an oven, and an electromagneticwave suppression material 12 made of an acrylamide polymer gel is prepared by performing a polymerization reaction and a crosslinking reaction of an acrylate monomer in the sheet. The electromagnetic wave suppression sheet 1 is formed.
Specific examples of acrylamide polymer gels include acrylamide as an acrylate monomer, N, N′-methylenebisacrylamide as a crosslinking agent, ammonium peroxodisulfate as a polymerization initiator, sodium chloride as an electrolyte, and ethylene as an alcohol. Glycol can be used. In this case, acrylamide is polymerized by ammonium peroxodisulfate, and at the same time, the cross-linking agent N, N′-methylenebisacrylamide is bonded to a part of the side chain of acrylamide to form a cross-link and has a three-dimensional network structure. Polyacrylamide is produced. The polyacrylamide absorbs the sodium chloride solution and ethylene glycol and swells to produce a polyacrylamide gel.
Next, the electromagneticwave suppression sheet 1 is taken out from the oven, the non-woven fabric 21 that is a tape-like base material is disposed on at least one of the surfaces, and the adhesive 22 is applied or immersed in the non-woven fabric 21 to form the adhesive layer 2. . And PET for peeling is stuck on the adhesive bond layer 2, and an electromagnetic wave suppression body is obtained.
In the present embodiment, the thickness (t2) ymm of the electromagneticwave suppression sheet 1 composed of the moisture- proof films 11a and 11b and an acrylate polymer gel containing x mass% of alcohols is expressed in xy coordinates (x, y). , A point (10, 1.0), b point (10, 3.0), and c point (20, 1.0) are molded into a region formed by connecting the three points. Freezing and high flame retardancy can be obtained.
Moreover, by adjusting the addition amount of electrolyte and alcohol, the electromagnetic wave suppression function can be exhibited stably without freezing the gel even in a low temperature environment. In particular, when the alcohol is added in the range of 10% by mass to 20% by mass, the electromagneticwave suppressing material 12 having a gel freezing point of −20 ° C. or lower is obtained by adding 3.0 mol / L or more of the electrolyte. be able to. As a result, the electromagnetic wave suppressing material 12 can stably exhibit the electromagnetic wave suppressing function without freezing the gel even in a low temperature environment. For example, in Japan, the electromagnetic wave suppressing material 12 can be used indoors and outdoors throughout the year. .
Examples Hereinafter, examples of the present invention will be described. In addition, a various change is possible for a present Example in the range which does not deviate from the summary of this invention.
<Manufacture of electromagnetic wave suppression sheet>
Hereinafter, the manufacturing method of the electromagnetic wave suppression sheet | seat which sealed the electromagnetic wave suppression material with the moisture proof film is demonstrated.
Pure water (68.62 g) with sodium chloride (8.01 g, manufactured by Kanto Chemical Co., Inc.), ethylene glycol (17.16 g, manufactured by Kanto Chemical Co., Ltd.), acrylamide (6.10 g, Wako Pure Chemical Industries, Ltd.) Co., Ltd.) and NN′-methylenebisacrylamide (0.07 g, manufactured by Wako Pure Chemical Industries, Ltd.) were blended and stirred with a stirrer until completely dissolved. Next, ammonium peroxodisulfate (0.04 g, manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator was added, and the mixture was sufficiently stirred with a stirrer until ammonium peroxodisulfate was completely dissolved.
As a result, the concentration of the mixed solution wassodium chloride 2 mol / L, ethylene glycol 20 wt%, acrylamide 1.0 mol / L, N, N′-methylenebisacrylamide 0.5 mol / L, and ammonium peroxodisulfate 0.2 mol / L. became.
Next, the mixed solution after stirring was placed in a vacuum oven depressurized at room temperature, and defoaming treatment was performed to remove oxygen from the mixed solution.
Next, as the moisture-proof film described above, Kureha Co., Ltd. Sereru (thickness of about 0.125 mm) is cut into a predetermined size, with the sealing surface that is the thermoplastic resin forming surface facing each other, with an impact sealer, A predetermined temperature was applied to laminate the three directions other than the mixed solution inlet, and a bag of moisture-proof film was produced.
Next, the moisture-proof film bag is inserted into a thicknessing jig assembled from a glass substrate and an aluminum plate spacer having a thickness required for the electromagnetic wave suppression sheet, and the mixed solution is injected into the super-moisture-proof film bag. Then fill. The impact sealer pushed out the overflowed mixed solution and closed the inlet of the moisture-proof film bag to form an electromagnetic wave suppression sheet.
Subsequently, a sheet filled with the mixed solution is sandwiched between thickening jigs and placed in an oven set at 60 ° C., and acrylamide polymerization reaction and crosslinking reaction are performed in the sheet to generate a polyacrylamide gel. . Thereby, an electromagnetic wave suppression sheet is manufactured. The electromagnetic wave suppression sheet which sealed the electromagnetic wave suppression material from the oven was taken out.
<Measurement of freezing point depression of electromagnetic wave suppression material>
In the production method described above, the freezing points of 16 types of electromagnetic wave suppression sheets (samples 1 to 16) when the sodium chloride concentration [mol / L] and the ethylene glycol concentration [wt%] were produced were measured. Table 1 shows the values of sodium chloride concentration [mol / L], ethylene glycol concentration [wt%] and freezing point [° C.] in Samples 1 to 16.
図１は、本実施の形態における電磁波抑制体の断面図である。この電磁波抑制体は、防湿フィルム１１ａ，１１ｂの間に電磁波抑制材料１２が封止されて構成される電磁波抑制シート１を有する。すなわち、電磁波抑制シート１は、防湿フィルム１１ａ，１１ｂの厚さｔ１と電磁波抑制材料１２の厚さとが加算される厚さｔ２を有する。なお、防湿フィルム１１ａ，１１ｂの厚さｔ１は、０．０５～０．２ｍｍ程度である。
防湿フィルム１１ａ，１１ｂは、優れた防湿性を有し、電磁波抑制材料の水分が蒸発するのを防止する。防湿フィルム１１ａ，１１ｂは、例えば、金属酸化物等の透湿防止用バリア層が形成されたＰＥＴ（polyethylene terephthalate）フィルムを熱可塑性樹脂にて複数枚ラミネートし、最表面である封止面に封止用熱可塑性樹脂を形成したものである。このような防湿フィルム１１ａ，１１ｂの一例として、株式会社クレハ製セレール（商標）が挙げられる。
電磁波抑制材料１２は、アルコール類と、電解質とを含有するアクリレート系高分子ゲルからなる。このゲル化合物は、アルコール類と電解質とを含有するため、ゲルの凍結点が降下し、低温環境においても電磁波抑制機能が安定的に維持される。
アルコール類は、不凍液として作用するものが用いられる。例えば、１級アルコール、２級アルコール、３級以上のアルコール類が挙げられる。具体的には、メタノール、エタノール、プロパノール、ブタノール、エチレングリコール（ＥＧ）、プロピレングリコール（ＰＧ）、ペンタエリスリトール等が挙げられ、その中でも、機能発現及び他の化合物との相互作用の観点から、グリコール類、特にエチレングリコールが最も好ましい。
電解質は、溶液の凝固点降下を引き起こすものが用いられる。例えば、高誘電率の極性溶媒に高い溶解度を有するものが挙げられる。上述の数式（１）中の誘電損失である第２項の誘電率ε’’が高い材料は、ＭＨｚ帯域、ＧＨｚ帯域の高周波数帯域において電磁波を効率的に吸収、抑制するため、電解質溶液をゲルに含有させることにより、高周波数帯域における電磁波吸収効率を高めることができる。
図２は、硝酸ナトリウム、硝酸カリウム、塩化カリウム、塩化ナトリウムの水への溶解度を示すグラフである。このグラフは、溶媒１００ｇに溶ける溶質の質量をグラム単位で表した数値で示したものである。この４種類の物質のうち、塩化カリウム及び塩化ナトリウムは、溶解度曲線の勾配が小さく、多少の温度変化でも結晶が析出する可能性が少ないため、イオンが安定的に維持される。
このような電解質としては、溶液中で完全にイオンに解離する強電解質であることが好ましく、例えば、塩化ナトリウム、塩化カリウム、塩化カルシウム、酢酸カリウム、酢酸カルシウム等が挙げられる。なお、酢酸カルシウムは保水性、拡散性を有するグリセリンとともに用いることにより電磁波抑制機能を持続的に維持することが可能となる。
アクリレート系高分子ゲルは、アクリレート系モノマーに重合開始剤及び架橋剤が添加されて得られる三次元の網目構造を有している。この三次元の網目構造は、重合開始剤がアクリレート系モノマー同士の連鎖反応を開始させ、架橋剤がアクリレート系高分子の側鎖の一部と連結する架橋の役割を果たすことにより形成されたものである。
このような電磁波抑制シート１において、アクリレート系高分子ゲルが、ｘ質量％のアルコール類を含有し、電磁波抑制シート１の厚さ（ｔ２）ｙｍｍが、ｘｙ座標（ｘ，ｙ）において、ａ点（１０，１．０）、ｂ点（１０，３．０）、及びｃ点（２０，１．０）の３点を結んで形成される領域内にあることが望ましい。これにより電磁波抑制シート１は、高い不凍性と高い難燃性を有することとなる。
また、本実施の形態における電磁波抑制体は、電磁波抑制シート１の少なくとも一方の面上に接着剤層２を有する。すなわち、接着剤層２は、防湿フィルム１１ａ，１１ｂの少なくとも一方に配される。
接着剤層２は、基材である不織布２１と、接着剤２２とを有する。また、電磁波抑制シート１と反対側の接着剤層２上には、剥離用ＰＥＴ（polyethylene terephthalate）が貼着される。そして、使用時にこれを剥離し、電磁波が発生する部位に接着剤層２を貼り付けることにより、電子機器に電磁波抑制体が搭載される。なお、接着剤層２の厚さは、１００μｍ～２００μｍ程度である。
不織布２１は、複数の原料を組み合わせたり、繊維長や太さなどの形状を調整したりすることで目的・用途に応じた機能を持たせることができる。これらの原料としては、例えば、アラミド繊維、ガラス繊維、セルロース繊維、ナイロン繊維、ビニロン繊維、ポリエステル繊維、ポリオレフィン繊維等を挙げることができる。
接着剤２２は、不織布２１からなるテープ状基材に塗布又は浸漬可能な粘着剤である。接着剤２２は、圧力が加えられることで被着材に対する流動性を持ち、また、剥離に対する凝集性を持つ。このような接着剤２２として、アクリル樹脂系樹脂が挙げられる。例えば、アクリル酸エステルモノマーを極性の高いモノマーと共重合させて接着剤を合成し、これをティッシュペーパー（不織布）に塗布すれば、両面テープを得ることができる。
また、接着剤２２は、難燃剤としてヘキサブロモベンゼン、三酸化アンチモン等を含有することが好ましい。これにより電磁波抑制体は、さらに高い難燃性を有することとなる。
このような電磁波抑制体は、電磁波抑制シート１が防湿フィルム１１ａ，１１ｂにより電磁波抑制材料１２を封止した構造であるため、その形状を十分に保持することができる。また、電磁波抑制体は、電磁波抑制機能を安定的に維持できる上、高い柔軟性を有するため、フレキシブルプリント基板等の複雑な形状の構造体に貼り付けることができる。
次に、本実施の形態における電磁波抑制体の製造方法について説明する。先ず、電解質、アルコール類、アクリレート系モノマー、架橋剤を溶媒に溶解させ、重合開始剤を入れて十分に攪拌する。
ここで、アクリレート系モノマーとしては、メチルアクリレート、エチルアクリレート、芳香族アクリレート、アクリルアミド等、１官能アクリレートであれば何れのものでもよく、特に、アルコール類や電解質との相互作用の観点から、アクリルアミドが最も好ましい。
また、架橋剤としては、例えば、２官能アクリレート、３官能以上のアクリレートが挙げられる。その中でも、アルコール類や電解質との相互作用の観点から、Ｎ，Ｎ’－アルキレンビスアクリルアミドが好ましく、Ｎ，Ｎ’－メチレンビスアクリルアミドが最も好ましい。また、架橋方法としては、熱架橋と光架橋とを併用した架橋方法を用いることが可能である。
また、重合開始剤としては、例えばラジカル開始剤が挙げられ、特に、アゾ系開始剤、過酸化物系開始剤が好ましい。その中でも、アルコール類や電解質との相互作用の観点から、ペルオキソ二硫酸アンモニウムが最も好ましい。
次に、常温で減圧した真空オーブン内に攪拌後の混合溶液を入れ、混合溶液内の酸素を抜く脱泡処理を行う。
次に、上述した防湿フィルム１１ａ，１１ｂを所定のサイズにカットし、熱可塑性樹脂形成面である封止面を向かい合わせにして、インパクトシーラにて、所定の温度を加えて、混合溶液の注入口以外の３方向をラミネートし、防湿フィルム１１ａ，１１ｂの袋を作製する。
次に、厚み出し治具に防湿フィルム１１ａ，１１ｂの袋を差し込み、この袋の中に混合溶液を注入して充填する。インパクトシーラにより、溢れ出た混合溶液を押し出しながら防湿フィルム１１ａ，１１ｂの袋の注入口を閉じて所定の厚さのシート形状にする。
次に、厚み出し治具に挟まれた所定の厚さのシートをオーブンに入れ、シート内でアクリレート系モノマーの重合反応及び架橋反応を行わせてアクリルアミド系高分子ゲルからなる電磁波抑制材料１２を生成し、電磁波抑制シート１を成型する。
具体的なアクリルアミド系高分子ゲルの一例として、アクリレート系モノマーとしてアクリルアミド、架橋剤としてＮ，Ｎ’－メチレンビスアクリルアミド、重合開始剤としてペルオキソ二硫酸アンモニウム、さらには、電解質として塩化ナトリウム、アルコール類としてエチレングリコールを用いることができる。この場合、ペルオキソ二硫酸アンモニウムによりアクリルアミドが重合され、これとともに、架橋剤のＮ，Ｎ’－メチレンビスアクリルアミドがアクリルアミドの一部の側鎖に結合して架橋を形成し、三次元の網目構造を有するポリアクリルアミドが生成される。そして、このポリアクリルアミドが塩化ナトリウム溶液及びエチレングリコールを吸収して膨潤することによりポリアクリルアミドゲルが生成される。
次に、オーブンから電磁波抑制シート１を取り出し、テープ状基材である不織布２１を少なくともどちらか一方の面に配し、接着剤２２を不織布２１に塗布又は浸漬させ、接着剤層２を形成する。そして、接着剤層２上に剥離用ＰＥＴを貼着し、電磁波抑制体を得る。
本実施の形態では、防湿フィルム１１ａ，１１ｂとｘ質量％のアルコール類を含有するアクリレート系高分子ゲルとからなる電磁波抑制シート１の厚さ（ｔ２）ｙｍｍを、ｘｙ座標（ｘ，ｙ）において、ａ点（１０，１．０）、ｂ点（１０，３．０）、及びｃ点（２０，１．０）の３点を結んで形成される領域内に成型することにより、高い不凍性と高い難燃性を得ることができる。
また、電解質及びアルコール類の添加量を調整することにより、低温環境においてもゲルを凍結させずに安定的に電磁波抑制機能を発揮させることができる。特に、アルコール類を１０質量％以上２０質量％以下の範囲で添加する場合において、電解質を３．０ｍｏｌ／Ｌ以上添加することにより、ゲルの凍結点が－２０℃以下の電磁波抑制材料１２を得ることができる。これにより、電磁波抑制材料１２は、低温環境においてもゲルが凍結せずに安定的に電磁波抑制機能を発揮でき、例えば日本国内では、一年を通じて屋内、屋外問わずほとんどの場所でも使用可能となる。
実施例
以下、本発明の実施例について説明する。なお、本実施例は、本発明の要旨を逸脱しない範囲で種々の変更が可能である。
＜電磁波抑制シートの製造＞
以下、電磁波抑制材料を防湿フィルムにより封止した電磁波抑制シートの製造方法について説明する。
純水（６８．６２ｇ）に塩化ナトリウム（８．０１ｇ、関東化学（株）社製）、エチレングリコール（１７．１６ｇ、関東化学（株）社製）、アクリルアミド（６．１０ｇ、和光純薬工業（株）社製）、Ｎ－Ｎ’－メチレンビスアクリルアミド（０．０７ｇ、和光純薬工業（株）社製）を配合し、完全に溶解するまでスターラで攪拌した。次に重合開始剤のペルオキソ二硫酸アンモニウム（０．０４ｇ、和光純薬工業（株）社製）を加え、ペルオキソ二硫酸アンモニウムが完全に溶解するまでスターラで十分攪拌した。
その結果、混合溶液の濃度は、 塩化ナトリウム ２ｍｏｌ／Ｌ、 エチレングリコール ２０ｗｔ％、 アクリルアミド １．０ｍｏｌ／Ｌ、 Ｎ，Ｎ’－メチレンビスアクリルアミド ０．５ｍｏｌ／Ｌ、 ペルオキソ二硫酸アンモニウム ０．２ｍｏｌ／Ｌとなった。
次に、常温で減圧した真空オーブン内に攪拌後の混合溶液を入れ、混合溶液内の酸素を抜く脱泡処理を行った。
次に、上述した防湿フィルムとして株式会社クレハ製セレール（厚さ約０．１２５ｍｍ）を所定のサイズにカットし、熱可塑性樹脂形成面である封止面を向かい合わせにして、インパクトシーラにて、所定の温度を加えて、混合溶液の注入口以外の３方向をラミネートし、防湿フィルムの袋を作製した。
次に、ガラス基板と電磁波抑制シートに必要な厚さを有するアルミ板のスペーサとから組み立てられた厚み出し治具に防湿フィルムの袋を差し込み、この超防湿フィルムの袋の中に混合溶液を注入して充填する。インパクトシーラにより、溢れ出た混合溶液を押し出しながら防湿フィルムの袋の注入口を閉じて電磁波抑制シートの形状にした。
続いて、厚み出し治具に混合溶液が充填されたシートを挟み、これを６０℃に設定されたオーブンに入れ、シート中でアクリルアミドの重合反応及び架橋反応を行わせてポリアクリルアミドゲルを生成させる。これにより電磁波抑制シートが製造される。オーブンから電磁波抑制材料を封止した電磁波抑制シートを取り出した。
＜電磁波抑制材料の凍結点降下測定＞
上述の製造方法において、塩化ナトリウム濃度〔ｍｏｌ／Ｌ〕及びエチレングリコール濃度〔ｗｔ％〕を変えて製造した場合の１６種類の電磁波抑制シート（サンプル１～１６）の凍結点を測定した。サンプル１～１６における塩化ナトリウム濃度〔ｍｏｌ／Ｌ〕、エチレングリコール濃度〔ｗｔ％〕及び凍結点〔℃〕の値を表１に示す。 Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view of an electromagnetic wave suppressing body in the present embodiment. This electromagnetic wave suppression body has the electromagnetic
The moisture-
The electromagnetic
Alcohols that act as antifreeze are used. For example, primary alcohols, secondary alcohols, tertiary alcohols and higher are listed. Specific examples include methanol, ethanol, propanol, butanol, ethylene glycol (EG), propylene glycol (PG), pentaerythritol and the like. Among these, glycols are used from the viewpoint of functional expression and interaction with other compounds. Most preferred are ethylene glycol.
An electrolyte that causes a freezing point depression of the solution is used. For example, those having high solubility in a polar solvent having a high dielectric constant can be mentioned. The material having a high dielectric constant ε ″ of the second term, which is the dielectric loss in the above-described formula (1), uses an electrolyte solution in order to efficiently absorb and suppress electromagnetic waves in the high frequency band of MHz band and GHz band. Inclusion in the gel can increase the electromagnetic wave absorption efficiency in the high frequency band.
FIG. 2 is a graph showing the solubility of sodium nitrate, potassium nitrate, potassium chloride, and sodium chloride in water. This graph shows the mass of a solute dissolved in 100 g of solvent as a numerical value expressed in grams. Of these four types of substances, potassium chloride and sodium chloride have a low solubility curve gradient and are less likely to precipitate crystals even with a slight temperature change, so that ions are stably maintained.
Such an electrolyte is preferably a strong electrolyte that dissociates completely into ions in a solution, and examples thereof include sodium chloride, potassium chloride, calcium chloride, potassium acetate, and calcium acetate. In addition, it becomes possible to maintain an electromagnetic wave suppression function continuously by using calcium acetate with glycerin having water retention and diffusibility.
The acrylate polymer gel has a three-dimensional network structure obtained by adding a polymerization initiator and a crosslinking agent to an acrylate monomer. This three-dimensional network structure is formed by a polymerization initiator that initiates a chain reaction between acrylate monomers, and a crosslinking agent that acts as a crosslink that links some of the side chains of the acrylate polymer. It is.
In such an electromagnetic
Moreover, the electromagnetic wave suppression body in the present exemplary embodiment has the
The
The
The adhesive 22 is a pressure-sensitive adhesive that can be applied to or immersed in a tape-shaped substrate made of the
The adhesive 22 preferably contains hexabromobenzene, antimony trioxide or the like as a flame retardant. Thereby, an electromagnetic wave suppression body will have a still higher flame retardance.
Since such an electromagnetic wave suppression body has a structure in which the electromagnetic
Next, the manufacturing method of the electromagnetic wave suppression body in this Embodiment is demonstrated. First, an electrolyte, an alcohol, an acrylate monomer, and a crosslinking agent are dissolved in a solvent, a polymerization initiator is added, and the mixture is sufficiently stirred.
Here, the acrylate monomer may be any monofunctional acrylate such as methyl acrylate, ethyl acrylate, aromatic acrylate, acrylamide, etc. In particular, from the viewpoint of interaction with alcohols and electrolytes, acrylamide may be used. Most preferred.
Examples of the crosslinking agent include bifunctional acrylates and trifunctional or higher acrylates. Among these, N, N′-alkylene bisacrylamide is preferable and N, N′-methylene bisacrylamide is most preferable from the viewpoint of interaction with alcohols and electrolytes. As a crosslinking method, a crosslinking method using both thermal crosslinking and photocrosslinking can be used.
Examples of the polymerization initiator include radical initiators, and azo initiators and peroxide initiators are particularly preferable. Among them, ammonium peroxodisulfate is most preferable from the viewpoint of interaction with alcohols and electrolytes.
Next, a defoaming process is performed in which the mixed solution after stirring is placed in a vacuum oven depressurized at room temperature, and oxygen is removed from the mixed solution.
Next, the moisture-
Next, a bag of moisture-
Next, a sheet having a predetermined thickness sandwiched between thickness-thickening jigs is put in an oven, and an electromagnetic
Specific examples of acrylamide polymer gels include acrylamide as an acrylate monomer, N, N′-methylenebisacrylamide as a crosslinking agent, ammonium peroxodisulfate as a polymerization initiator, sodium chloride as an electrolyte, and ethylene as an alcohol. Glycol can be used. In this case, acrylamide is polymerized by ammonium peroxodisulfate, and at the same time, the cross-linking agent N, N′-methylenebisacrylamide is bonded to a part of the side chain of acrylamide to form a cross-link and has a three-dimensional network structure. Polyacrylamide is produced. The polyacrylamide absorbs the sodium chloride solution and ethylene glycol and swells to produce a polyacrylamide gel.
Next, the electromagnetic
In the present embodiment, the thickness (t2) ymm of the electromagnetic
Moreover, by adjusting the addition amount of electrolyte and alcohol, the electromagnetic wave suppression function can be exhibited stably without freezing the gel even in a low temperature environment. In particular, when the alcohol is added in the range of 10% by mass to 20% by mass, the electromagnetic
Examples Hereinafter, examples of the present invention will be described. In addition, a various change is possible for a present Example in the range which does not deviate from the summary of this invention.
<Manufacture of electromagnetic wave suppression sheet>
Hereinafter, the manufacturing method of the electromagnetic wave suppression sheet | seat which sealed the electromagnetic wave suppression material with the moisture proof film is demonstrated.
Pure water (68.62 g) with sodium chloride (8.01 g, manufactured by Kanto Chemical Co., Inc.), ethylene glycol (17.16 g, manufactured by Kanto Chemical Co., Ltd.), acrylamide (6.10 g, Wako Pure Chemical Industries, Ltd.) Co., Ltd.) and NN′-methylenebisacrylamide (0.07 g, manufactured by Wako Pure Chemical Industries, Ltd.) were blended and stirred with a stirrer until completely dissolved. Next, ammonium peroxodisulfate (0.04 g, manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator was added, and the mixture was sufficiently stirred with a stirrer until ammonium peroxodisulfate was completely dissolved.
As a result, the concentration of the mixed solution was
Next, the mixed solution after stirring was placed in a vacuum oven depressurized at room temperature, and defoaming treatment was performed to remove oxygen from the mixed solution.
Next, as the moisture-proof film described above, Kureha Co., Ltd. Sereru (thickness of about 0.125 mm) is cut into a predetermined size, with the sealing surface that is the thermoplastic resin forming surface facing each other, with an impact sealer, A predetermined temperature was applied to laminate the three directions other than the mixed solution inlet, and a bag of moisture-proof film was produced.
Next, the moisture-proof film bag is inserted into a thicknessing jig assembled from a glass substrate and an aluminum plate spacer having a thickness required for the electromagnetic wave suppression sheet, and the mixed solution is injected into the super-moisture-proof film bag. Then fill. The impact sealer pushed out the overflowed mixed solution and closed the inlet of the moisture-proof film bag to form an electromagnetic wave suppression sheet.
Subsequently, a sheet filled with the mixed solution is sandwiched between thickening jigs and placed in an oven set at 60 ° C., and acrylamide polymerization reaction and crosslinking reaction are performed in the sheet to generate a polyacrylamide gel. . Thereby, an electromagnetic wave suppression sheet is manufactured. The electromagnetic wave suppression sheet which sealed the electromagnetic wave suppression material from the oven was taken out.
<Measurement of freezing point depression of electromagnetic wave suppression material>
In the production method described above, the freezing points of 16 types of electromagnetic wave suppression sheets (
図３において、ポリアクリルアミドゲルの凍結点は、塩化ナトリウム濃度〔ｍｏｌ／Ｌ〕の増加に伴って降下した。また、ポリアクリルアミドゲルの凍結点は、エチレングリコール濃度〔ｗｔ％〕の増加に伴って降下した。
この図３からも分かるように、塩化ナトリウム濃度が１．０ｍｏｌ／Ｌである場合、エチレングリコール濃度が１０～２５ｗｔ％の何れであってもポリアクリルアミドゲルの凍結点は－２０℃以下にはならなかった。
＜電磁波抑制体の難燃性測定＞
電磁波抑制体の燃焼試験は、ＵＬ（Underwriter Laboratories Inc.）耐炎性試験規格ＵＬ９４に準じて行った。垂直に支持した短冊状の試験片（１２５±５ｍｍ×１３±０．５ｍｍ×厚さｍｍ）の下端にバーナー炎をあてて１０秒間保ち、その後バーナー炎を試験片から離し、炎が消えれば直ちにバーナー炎を更に１０秒間あてたのちバーナー炎を離して判定を行った。判定は、１回目と２回目の接炎終了後の有炎燃焼持続時間、２回目の接炎終了後の有炎燃焼持続時間及び無炎燃焼持続時間の合計、５本の試験片の有炎燃焼時間の合計、並びに燃焼滴下物（ドリップ）の有無で判定した。Ｖ０判定は、１回目、２回目共に１０秒以内、Ｖ１,Ｖ２判定は、２０秒以内に有炎燃焼を終えた場合とした。更に２回目の有炎燃焼持続時間と無炎燃焼時間の合計が、Ｖ０判定は３０秒以内、Ｖ１,Ｖ２判定は６０秒以内で消えた場合とした。更に５本の試験片の有炎燃焼時間の合計が、Ｖ０判定は５０秒以内、Ｖ１,Ｖ２判定は２５０秒以内の場合とした。なお、燃焼落下物はＶ２のみに許容され、すべての試験片は燃え尽きてはいけない。
上述した製造方法により得られた電磁波抑制シートのみからなる試験片は、燃え尽きてしまった。そこで、試験片の片面に難燃性の接着剤層を設けて燃焼試験を行った。
難燃性の接着剤層としては、厚さ約１５０μｍの感圧両面接着テープＵＴ１５１５（ソニーケミカル＆インフォメーションデバイス（株）製）を用いた。この感圧両面接着テープは、不織布として新富士製紙（株）製コンロンＩ（厚さ約４０μｍ）を含有し、難燃剤としてヘキサブロモベンゼン（ＨＢＢ：Ｃ６Ｂｒ６）を３０～４０質量％、三酸化アンチモン（Ｓｂ２Ｏ３）を５～１０質量％含有している。
［試験片１］
上述の製造方法において塩化ナトリウム濃度を３ｍｏｌ／Ｌとし、エチレングリコール濃度を１０質量％として、短冊状の電磁波抑制シート（１２５±５ｍｍ×１３±０．５ｍｍ×厚さ０．５ｍｍ）を得た。そして、この電磁波抑制シートの片面に全面に亘って感圧両面接着テープＵＴ１５１５を貼り付け、試験片１を作製した。
［試験片２］
短冊状の電磁波抑制シートの厚さを１．０ｍｍとした以外は、試験片１と同様にして試験片２を作製した。
［試験片３］
短冊状の電磁波抑制シートの厚さを２．０ｍｍとした以外は、試験片１と同様にして試験片３を作製した。
［試験片４］
短冊状の電磁波抑制シートの厚さを３．０ｍｍとした以外は、試験片１と同様にして試験片４を作製した。
［試験片５］
エチレングリコール濃度を２０質量％とした以外は、試験片１と同様にして試験片５を作製した。
［試験片６］
エチレングリコール濃度を２０質量％とし、短冊状の電磁波抑制シートの厚さを１．０ｍｍとした以外は、試験片１と同様にして試験片６を作製した。
［試験片７］
エチレングリコール濃度を２０質量％とし、短冊状の電磁波抑制シートの厚さを２．０ｍｍとした以外は、試験片１と同様にして試験片７を作製した。
［試験片８］
エチレングリコール濃度を２０質量％とし、短冊状の電磁波抑制シートの厚さを３．０ｍｍとした以外は、試験片１と同様にして試験片８を作製した。
［試験片９］
エチレングリコール濃度を２０質量％とし、短冊状の電磁波抑制シートの厚さを１．０ｍｍとし、ＵＴ１５１５と同じ樹脂で構成され、基材の不織布を含有しない接着剤層を設けた以外は、試験片１と同様にして試験片９を作製した。
［試験片１０］
エチレングリコール濃度を２０質量％とし、短冊状の電磁波抑制シートの厚さを２．０ｍｍとし、ＵＴ１５１５と同じ樹脂で構成され、基材の不織布を含有しない接着剤層を設けた以外は、試験片１と同様にして試験片１０を作製した。
［試験片１１］
エチレングリコール濃度を１０質量％とし、短冊状の電磁波抑制シートの厚さを３．０ｍｍとし、ＵＴ１５１５と同じ樹脂で構成され、基材の不織布を含有しない接着剤層を設けた以外は、試験片１と同様にして試験片１１を作製した。
なお、エチレングリコール濃度を３０質量％とした場合、ポリアクリルアミドゲルの硬化不良が発生し、所定の厚さの電磁波抑制シートが製造できなかった。また、厚さが３．５ｍｍ以上の試験片は、実機の規定上製造できなかった。
表２に、試験片１～８の燃焼試験の結果を示し、表３に試験片９～１１の燃焼試験の結果を示す。
In FIG. 3, the freezing point of the polyacrylamide gel decreased as the sodium chloride concentration [mol / L] increased. In addition, the freezing point of the polyacrylamide gel decreased as the ethylene glycol concentration [wt%] increased.
As can be seen from FIG. 3, when the sodium chloride concentration is 1.0 mol / L, the freezing point of the polyacrylamide gel does not fall below −20 ° C. regardless of the ethylene glycol concentration of 10 to 25 wt%. There wasn't.
<Measurement of flame retardancy of electromagnetic wave suppressor>
The combustion test of the electromagnetic wave suppressor was performed according to UL (Underwriter Laboratories Inc.) flame resistance test standard UL94. Apply a burner flame to the lower end of a strip-shaped test piece (125 ± 5 mm × 13 ± 0.5 mm × thickness mm) supported vertically and keep it for 10 seconds, then remove the burner flame from the test piece and immediately after the flame disappears The burner flame was further applied for 10 seconds, and then the burner flame was released to make a judgment. Judgment is the sum of the flaming combustion duration after the end of the first and second flame contact, the flaming combustion duration and the non-flame duration after the second flame contact, and the flaming of 5 test pieces Judgment was made based on the total combustion time and the presence or absence of combustion drops (drip). The V0 determination was made within 10 seconds for both the first time and the second time, and the V1 and V2 determinations were made when flaming combustion was finished within 20 seconds. Furthermore, the sum of the second flammable combustion duration and the flameless combustion time was assumed to have disappeared within 30 seconds for the V0 determination and within 60 seconds for the V1, V2 determination. Furthermore, the total of the flammable combustion times of the five test pieces was determined to be within 50 seconds for V0 determination and within 250 seconds for V1, V2 determination. In addition, the burning fall object is permitted only to V2, and all the test pieces must not be burned out.
The test piece which consists only of the electromagnetic wave suppression sheet obtained by the manufacturing method mentioned above was burned out. Therefore, a flame test was performed by providing a flame retardant adhesive layer on one side of the test piece.
As the flame retardant adhesive layer, a pressure-sensitive double-sided adhesive tape UT1515 (manufactured by Sony Chemical & Information Device Co., Ltd.) having a thickness of about 150 μm was used. This pressure-sensitive double-sided adhesive tape contains Konron I (thickness: about 40 μm) manufactured by Shin-Fuji Paper Co., Ltd. as a nonwoven fabric, and hexabromobenzene (HBB: C 6 Br 6 ) as a
[Test piece 1]
In the above production method, a strip-shaped electromagnetic wave suppression sheet (125 ± 5 mm × 13 ± 0.5 mm × thickness 0.5 mm) was obtained with a sodium chloride concentration of 3 mol / L and an ethylene glycol concentration of 10% by mass. And the pressure sensitive double-sided adhesive tape UT1515 was affixed over the whole surface of one side of this electromagnetic wave suppression sheet, and the
[Test piece 2]
[Test piece 3]
A test piece 3 was produced in the same manner as the
[Test piece 4]
A test piece 4 was produced in the same manner as the
[Test piece 5]
[Test piece 6]
A test piece 6 was prepared in the same manner as the
[Test piece 7]
A test piece 7 was prepared in the same manner as the
[Test piece 8]
A test piece 8 was produced in the same manner as the
[Test piece 9]
The test piece except that the ethylene glycol concentration was 20% by mass, the thickness of the strip-shaped electromagnetic wave suppression sheet was 1.0 mm, and the adhesive layer which was made of the same resin as UT1515 and did not contain the base nonwoven fabric was provided. In the same manner as in Example 1, a test piece 9 was produced.
[Test piece 10]
The test piece except that the ethylene glycol concentration is 20% by mass, the thickness of the strip-shaped electromagnetic wave suppression sheet is 2.0 mm, the adhesive layer is made of the same resin as that of UT1515 and does not contain the nonwoven fabric of the base material. In the same manner as in Example 1, a
[Test piece 11]
The test piece except that the ethylene glycol concentration is 10% by mass, the thickness of the strip-shaped electromagnetic wave suppression sheet is 3.0 mm, and the adhesive layer is made of the same resin as UT1515 and does not contain the non-woven fabric of the base material. A test piece 11 was produced in the same manner as in Example 1.
In addition, when the ethylene glycol concentration was 30% by mass, poor curing of the polyacrylamide gel occurred, and an electromagnetic wave suppression sheet having a predetermined thickness could not be produced. Further, a test piece having a thickness of 3.5 mm or more could not be manufactured due to the specification of the actual machine.
Table 2 shows the results of the burning test of the
また、エチレングリコール濃度が２０質量％の試験片５～８において、厚さが０．５ｍｍの試験片５は、ゲル量が少ないため水分も少なく、難燃性が発現しなかったものと考えられる。また、厚さが１．０ｍｍの試験片６は、Ｖ１の難燃性を発現したが、厚さが２．０ｍｍ以上の試験片７，８は、燃え尽きてしまい、難燃性を発現しなかった。これは、厚さの増加に伴いゲル組成物に含まれるエチレングリコール量が多くなったためだと考えられる。
すなわち、防湿フィルムとｘ質量％のエチレングリコールを含有するポリアクリレートゲルとからなる電磁波抑制シートの厚さｙｍｍを、ｘｙ座標（ｘ，ｙ）において、ａ点（１０，１．０）、ｂ点（１０，３．０）、及びｃ点（２０，１．０）の３点を結んで形成される領域内に成型することにより、高い不凍性と高い難燃性が得られることが分かった。
また、表３に示すように、ＵＴ１５１５と同じ樹脂で構成され、基材の不織布を含有しない接着剤層を設けた試験片９～１１は、すべて燃え尽きてしまい、難燃性を発現しなかった。ここで、試験片６と試験片９、又は試験片４と試験片１１を比較すると分かるように、不織布と難燃性接着剤とを含有する接着剤層を設けることにより、高い難燃性が得られることが分かった。
In addition, in the
That is, the thickness ymm of the electromagnetic wave suppression sheet composed of a moisture-proof film and a polyacrylate gel containing x mass% ethylene glycol is represented by points a (10, 1.0) and b in xy coordinates (x, y). It is found that high antifreeze and high flame retardancy can be obtained by molding in the region formed by connecting three points (10, 3.0) and c point (20, 1.0). It was.
Further, as shown in Table 3, all of the test pieces 9 to 11 made of the same resin as UT1515 and provided with an adhesive layer not containing a nonwoven fabric as a base material burned out and did not exhibit flame retardancy. . Here, as can be seen by comparing the test piece 6 and the test piece 9, or the test piece 4 and the test piece 11, by providing an adhesive layer containing a non-woven fabric and a flame-retardant adhesive, high flame retardancy is achieved. It turns out that it is obtained.
Claims (12)
- １．第１の防湿フィルムと、第２の防湿フィルムと、前記第１の防湿フィルムと前記第２の防湿フィルムとの間に封止されるアクリレート系高分子ゲルとからなる電磁波抑制シートを有し、
前記アクリレート系高分子ゲルが、ｘ質量％のアルコール類を含有し、
前記電磁波抑制シートの厚さｙｍｍが、ｘｙ座標（ｘ，ｙ）において、ａ点（１０，１．０）、ｂ点（１０，３．０）、及びｃ点（２０，１．０）の３点を結んで形成される領域内にある電磁波抑制体。 1. An electromagnetic wave suppressing sheet comprising a first moisture-proof film, a second moisture-proof film, and an acrylate polymer gel sealed between the first moisture-proof film and the second moisture-proof film;
The acrylate polymer gel contains x mass% alcohols,
The thickness ymm of the electromagnetic wave suppression sheet is a point (10, 1.0), b point (10, 3.0), and c point (20, 1.0) in xy coordinates (x, y). An electromagnetic wave suppressor in a region formed by connecting three points. - ２．前記アルコール類が、メタノール、エタノール、プロパノール、ブタノール、エチレングリコール、プロピレングリコール、ペンタエリスリトールのうち少なくとも１種である請求の範囲第１項記載の電磁波抑制体。 2. The electromagnetic wave suppressor according to claim 1, wherein the alcohol is at least one of methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol, and pentaerythritol.
- ３．前記アクリレート系高分子ゲルが、電解質を含有し、
前記電解質が、塩化ナトリウム、塩化カリウム、塩化カルシウム、酢酸カリウム、酢酸カルシウムのうち少なくとも１種である請求の範囲第１項記載の電磁波抑制体。 3. The acrylate polymer gel contains an electrolyte,
The electromagnetic wave suppressor according to claim 1, wherein the electrolyte is at least one of sodium chloride, potassium chloride, calcium chloride, potassium acetate, and calcium acetate. - ４．前記電解質が、前記アクリレート系高分子ゲルの硬化前の組成物に３．０ｍｏｌ／Ｌ以上添加されている請求の範囲第３項記載の電磁波抑制体。 4). The electromagnetic wave suppressor according to claim 3, wherein the electrolyte is added in an amount of 3.0 mol / L or more to the composition before curing of the acrylate polymer gel.
- ５．前記第１の防湿フィルム、前記第２の防湿フィルムの少なくともどちらか一方の面に不織布を基材とする接着剤層を有する請求の範囲第１項乃至第４項いずれか１項記載の電磁波抑制体。 5. The electromagnetic wave suppression according to any one of claims 1 to 4, further comprising an adhesive layer based on a nonwoven fabric on at least one of the first moisture-proof film and the second moisture-proof film. body.
- ６．前記接着剤層が、ヘキサブロモベンゼン及び三酸化アンチモンを含有する請求の範囲第５項記載の電磁波抑制体。 6). 6. The electromagnetic wave suppressor according to claim 5, wherein the adhesive layer contains hexabromobenzene and antimony trioxide.
- ７．第１の防湿フィルムと第２の防湿フィルムとの間に、ｘ質量％のアルコール類と、アクリレート系モノマーと、重合開始剤とを含有する組成物を注入して密閉し、
前記第１の防湿フィルムと、前記第２の防湿フィルムと、前記組成物がゲル化したアクリレート系高分子ゲルとからなる電磁波抑制シートの厚さｙｍｍを、ｘｙ座標（ｘ，ｙ）において、ａ点（１０，１．０）、ｂ点（１０，３．０）、及びｃ点（２０，１．０）の３点を結んで形成される領域内に成型する電磁波抑制体の製造方法。 7). Between the first moisture-proof film and the second moisture-proof film, a composition containing x mass% alcohol, an acrylate monomer, and a polymerization initiator is injected and sealed,
The thickness ymm of the electromagnetic wave suppression sheet composed of the first moisture-proof film, the second moisture-proof film, and the acrylate polymer gel in which the composition is gelled is expressed as a in xy coordinates (x, y), a A method of manufacturing an electromagnetic wave suppressor that is molded into a region formed by connecting three points of a point (10, 1.0), a point b (10, 3.0), and a point c (20, 1.0). - ８．前記アルコール類が、メタノール、エタノール、プロパノール、ブタノール、エチレングリコール、プロピレングリコール、ペンタエリスリトールのうち少なくとも１種である請求の範囲第７項記載の電磁波抑制体の製造方法。 8). The method for producing an electromagnetic wave suppressor according to claim 7, wherein the alcohol is at least one of methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol, and pentaerythritol.
- ９．前記組成物が、電解質を含有し、
前記電解質が、塩化ナトリウム、塩化カリウム、塩化カルシウム、酢酸カリウム、酢酸カルシウムのうち少なくとも１種である請求の範囲第７項記載の電磁波抑制体の製造方法。 9. The composition contains an electrolyte;
The method for producing an electromagnetic wave suppressor according to claim 7, wherein the electrolyte is at least one of sodium chloride, potassium chloride, calcium chloride, potassium acetate, and calcium acetate. - １０．前記電解質が、前記組成物に３．０ｍｏｌ／Ｌ以上添加されている請求の範囲第９項記載の電磁波抑制体の製造方法。 10. The method for producing an electromagnetic wave suppressor according to claim 9, wherein the electrolyte is added to the composition in an amount of 3.0 mol / L or more.
- １１．前記電磁波抑制シートを成型した後、前記第１の防湿フィルム、前記第２の防湿フィルムの少なくともどちらか一方の平面に不織布を基材とする接着剤層を形成する請求の範囲第７項乃至第１０項いずれか１項記載の電磁波抑制体の製造方法。 11. 8. An adhesive layer comprising a nonwoven fabric as a base material is formed on at least one of the first moisture-proof film and the second moisture-proof film after molding the electromagnetic wave suppression sheet. The manufacturing method of the electromagnetic wave suppression body of any one of 10 items.
- １２．前記接着剤層が、ヘキサブロモベンゼン及び三酸化アンチモンを含有する請求の範囲第１１項記載の電磁波抑制体の製造方法。 12 The method for producing an electromagnetic wave suppressor according to claim 11, wherein the adhesive layer contains hexabromobenzene and antimony trioxide.
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| CN200880015558XA CN101715658B (en) | 2008-04-14 | 2008-12-02 | Electromagnetic wave inhibitor and process for producing the electromagnetic wave inhibitor |
| US12/597,988 US20100116543A1 (en) | 2008-04-14 | 2008-12-02 | Electromagnetic wave suppressor and method for manufacturing the same |
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| US8759692B2 (en) | 2010-08-30 | 2014-06-24 | Parker-Hannifin Corporation | Encapsulated expanded crimped metal mesh for sealing, EMI shielding and lightning strike applications |
| CN109413971A (en) * | 2017-08-15 | 2019-03-01 | 深圳富泰宏精密工业有限公司 | Shielded box and rf attenuation control method |
| CN112585009A (en) * | 2019-06-07 | 2021-03-30 | 日东电工株式会社 | Radio wave absorbing member, radio wave absorbing structure, and inspection device |
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| JP2006073991A (en) * | 2004-08-02 | 2006-03-16 | Sony Corp | Electromagnetic wave suppressing material, electromagnetic wave suppressing device and electronic equipment |
| JP2006319048A (en) * | 2005-05-11 | 2006-11-24 | Sony Corp | Electromagnetic-wave suppressive material, electromagnetic-wave suppressive device, and electronic machine |
| JP2007027470A (en) * | 2005-07-19 | 2007-02-01 | Sony Corp | Electromagnetic wave suppressing material and electronic equipment |
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| WO2000023513A1 (en) * | 1998-10-22 | 2000-04-27 | Parker-Hannifin Corporation | Intumescent, flame retardant pressure sensitive adhesive composition for emi shielding applications |
| DE10111790A1 (en) * | 2001-03-12 | 2002-09-26 | Bayer Ag | New polythiophene dispersions |
| JP3998975B2 (en) * | 2001-12-28 | 2007-10-31 | 大日本印刷株式会社 | Electromagnetic wave shielding sheet |
| JP2004140283A (en) * | 2002-10-21 | 2004-05-13 | Nisshinbo Ind Inc | Thin electromagnetic wave shield layered product for display and method for manufacturing the same |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2006073991A (en) * | 2004-08-02 | 2006-03-16 | Sony Corp | Electromagnetic wave suppressing material, electromagnetic wave suppressing device and electronic equipment |
| JP2006319048A (en) * | 2005-05-11 | 2006-11-24 | Sony Corp | Electromagnetic-wave suppressive material, electromagnetic-wave suppressive device, and electronic machine |
| JP2007027470A (en) * | 2005-07-19 | 2007-02-01 | Sony Corp | Electromagnetic wave suppressing material and electronic equipment |
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| JP2009259905A (en) | 2009-11-05 |
| CN101715658B (en) | 2012-06-20 |
| JP4993380B2 (en) | 2012-08-08 |
| US20100116543A1 (en) | 2010-05-13 |
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